Photocopiable Classroom Exercises Decade for Natural Disaster Reduction HAZARD-WISE on Natural Hazards and Disasters Chris Dolan ~ I N AUSTRALIA An Australian Disaster Awareness Project for the International Printed in Australia by National Capital Printing, 22 Pine Street, Fyshwick ACT 2609. ACKNOWLEDGMENT The author would like to thank the following for their invaluable help in the preparation of this book: Peter May, Manager of the Disaster Awareness Program, Emergency Management Australia; the Bureau of Meteorology, Melbourne, VIC and Adelaide, SA; The Advertiser newspaper, Adelaide SA; The Shepparton News, VIC; The Courier Mail, Brisbane, QLD; Bob Brooks of World Vision; Austcare and Enver Malkic. Cover: (left to right) Row I Summer bushfire, VIC. 2 West seasons floods, NT. 3 Mt Tavurvur eruption, Rabaul, PNG, 1994. 4 Earthquake ground rupture, near Tennant Creek, NT, 1988. 5 Tropical cyclone viewed from space. 6 Drought scene, SA. 6 Tornado near Cleve, SA, 1989. Published February 1995 Pages and sections may be reproduced by school teachers without specific approval. ISBNO 642 224358 Published by Emergency Management Australia (EMA) on behalf of the Australian Coordination Committee for the International Decade for Natural Disaster Reduction. Researched and written by Chris Dolan with assistance from Peter May (EMA). Final edit, cover design and preparation by Peter May. FOREWORD At the beginning of the International Decade for Natural Disaster Reduction (IDNOR), National IDNDR Committees were invited by the United Nations to develop their strategies for the Decade. Under the challenge ‘What can the National Committee do?’ was the suggestion of Promoting Public Education and Information. The explanation stated: ‘This will involve following a full range of creative activities including cooperation with the news media as well as preparing material to be used in schools and colleges’. The Australian IDNDR Coordination Committee decided that education and training would be a key activity in the framework of action for the International Decade. To date, the Australian IDNDR Coordination Committee has been involved in the following activities in the fields of education, training and media campaigns: • Production and public dissemination of: — ‘Australia’s Natural Hazard Zones’ poster map; — ‘Hazards, Disasters and Survival - A Booklet for Schools and the Community’; — ‘Emergency/Disaster Planning for Principals’ (a handbook for heads of educational institutions); and — a comprehensive range of information pamphlets and action guides on disaster prevention and preparedness for householders. • Television and radio disaster awareness campaigns in the form of cartoon-style Community Service Announcements covering Cyclones, Bushfires, Severe Storms and Hoods. • In conjunction with the ANU Centre for Resource and Environmental Studies, conduct of a seminar for World Disaster Reduction Day 1993 on the theme ‘Education for Disaster Reduction’. • Sponsorship of the publication ‘Learning to Live Safely in the Australian Environment’ produced by the Australian Geography Teachers Association. Now we can add ‘Hazard-Wise’, which builds upon ‘Learning to Live Safely in the Australian Environment’ and focuses on the Education and Community Awareness requirements for IDNDR. It should not only prove to be of great practical benefit to teachers, students and the public, but also it will raise the profile of Australian IDNDR activities. ‘Hazard-Wise’ provides the teacher with a ready-to-use classroom resource which covers many aspects of major natural hazards and disasters. Through a series of exercises, students are stimulated to investigate the causes and effects of hazards and the way in which people can respond effectively to them. Well-known Australian case studies are used to illustrate the impact of natural disasters. Each section also contains activities designed to arouse greater interest in the topic such as crossword puzzles, research activities and role-play exercises. I commend Chris Dolan for his initiative in developing this project. it is one that received very ready acceptance from members of the IDNDR Coordinating Committee. With its attractive layout and captivating subject matter, ‘Hazard-Wise’ is a most valuable addition to existing teaching resources on hazards and disasters. jb4-%, k-~4~ Alan Hodges Chairman Australian IDNTJR Coordination Committee Ill CONTENTS Foreword j Contents iii Section 1 An Introduction to Hazards and Disasters 1 Section 2 The Bushfire Hazard 13 Section 3 The Flood Hazard 27 Section 4 The Severe Storm Hazard 41 Section 5 The Tropical Cyclone Hazard 51 Section 6 The Drought Hazard 67 Section 7 The Earthquake Hazard 83 Section 8 The Volcano Hazard 98 Self Check Answers 109 In this section 2 3 4 6 B 9 10 12 Section 1 An Introduction to Hazards and Disasters Page • Hazards and Disasters: Glossary of Key Terms • 1-Ia zard or Disaster? • CLassifying Hazards • Find-~word: Hazards and Disasters • How Hazards arid Disasters Vary • Perception of t-Iazards • Elazards and Disasters in the Newspapers • R~c~’.rcIi Assignment: Natural and Human-Caused Disasters Hazards and Disasters: Glossary of Key Terms Atmospheric hazards: Hazards which are associated with our weather and climate: e.g. tropical cyclones, drought and hailstorms. Biological hazards: Hazards which are caused or spread by plants and animals: e.g. plagues, pests and bushfires. Disasters: Hazardous events which are bigger, more frequent or happens for longer than would normally be expected, and/or involves excessive damage to life and property. Emergency management: A process which is used in potentially hazardous situations to minimise uncertainties and maximise public safety. It typically involves the stages of hazard analysis, prevention and mitigation, preparedness, response and recovery. Geological hazards: Hazards caused by processes which operate inside the earth: e.g. earthquakes and volcanoes. Geomorphological hazards: Hazards caused by processes which occur on the surface of the earth or ocean: e.g. floods, tsunamis and landslides. Hazard: An event either natural or human-caused which involves a risk of damage to people and property. Hazard perception: A view which an individual has of a natural or human-made hazard. Human-caused hazards: Hazards which do not involve natural processes iii any major way, but are caused by human activity alone: e.g. oil spills, war, transport accidents. Natural hazards: Hazards which occur when extreme natural events, such as intense rainfall, very strong winds or earth movement, interact with human activities, such as transport, industry or settlement. A S C NATURAL HAZARD Fi~urr U Extreme nacural event, (L~cur~J ha~rd or nattr~1 dtsas4cr Figure 2! Darrt.ipe co h~inirg IOL]cFWiFLg CycLone iracy. I)arwin. [974 Seclion I ,InJiitn~djax~on fri Hazards wrd Disquers shuwn a~ ‘naturat’ or ‘huniart-caused’ Hazard or Disaster? HAZARD DATA Huards hwoh~e a ri4~ ut tbm~e tct peopk and pro~xrly. Natural hazards ocmJr when ext r~rqc naWra] evtnls, such ~s hea% ‘~ ram, s(rcilg winds ~r earth move me i-il, interact wLIh human .‘~ccIci!Ies, such a~ tnnsport, indusiry or ~elL!ement (Figure I) + ~Human-caused~ haznrds do !loL invojvc n~tur~Ll proct~ses in a]lv major way, but are eau~cd by human activity aIon~ A hazard becomes a di~a~tcr wher~: (a~ it is big get, more freqt~ctu ~r happens for Longer (han wou]d nonnu]iy be eq~Cc!ed~ r (bi C.XcC~.ALVe ciari-tage F~) Lite 3miJ pn)per(y IE thvo~ved. Activities I Study Figure 1. a Explain what is happening in e~ich section ol the sketch. b Why is the overlapping sec hon idealif led a~ the area where a natural haxard is present? c Draw an alteted version of the sketch to thow that a aatur~d dts~tster ha-c occuxred. Thq~Mn the aLterations vtn, have made. 2 Would you describe the scene in Figure 2 as a ~natural disaster2 Explain your answer. 3 Study P~gu~ 3. a ExjMath whethar ~ci~ would describe the even~ Figure3~ Th~rCoodc Iskind rtr-~s, Mtlhoirnle, 1991 b What 3ddLL~ona[ infnrmatw~ i.v~iuld you need to know be~ore c[a~sifvirtg thE: t’\’ent a; a ‘hazard’ or a ‘dis*tvr7 4 In I 9%. ma~or I ire~ swepi thr~r~glt :ore5ts or’ the Galapagos lai~s. oh th~ cL~lst t~7 South Arneriea. A number i~innt turtles, for which tHi’ i5lallcIs are fatnous, were kUleá in t]u’ I~re.;, hut there w~m no loss of human life. Would voti t:~!j ~‘ch ~in cr~t a naftirat dFsater E\plaIn your an~cer. I’i~ure 1 Dusracorm r~ngtiIIing %fctbovrne at ihe end eta major droughi. Fcbniary, LUU ~‘idapfedfmrn I:si by C~’Iu~ Witson, 1u.ur~thun Ertiergetiçy Mwiagenreni Iir.i,rrtwe, Mi M~tc~J~rn. Victnria CLPIIUL. Section I ___________ An ftitroduction to f/azaids wij Disasrer.s Classifying Hazards Figurr 2; Li.’i of hazards wh]ch can bcccirrtt d.sasicrs HAZARD DA1.tA • Hazards (aid ths-asrs) ca~ be class tEed according to how they arc caused. • NaturaL hazards c-an be ccmsidcred in four caregüa-iss’ a Grtokgicrz! hawrds - those caused by processes which operate inside the earth. e.g. earthquakes acid ~olcartoea. I, Geoinorphalcgical hazards - thctie caused by processes which occur cm tl~ surface of the earth (or ocean). e.g. ficods, Lsurtands and landslides. e Atmosphenc Mzaths - those which are associatcd with our weather and climate: e.g. tropica’ cyclones. dtotughc and haihct1rrns. d Bkdo~gwaI haztirds - those which are caused or spread by plans and aaimals: e.g. plagues1 pt~sms and bushfires. • Human-caused hazards arc those which do not involve ~iatural proeesse~ in any major way. but are caused by humait activity alonc e g. oil spills, war transport acczdcrics Arronaoiical and space debris Astetoid / corneL impact AvaLanche Blizzard / snowstorm I3omb thr~ot Bridge cDlhipse Built] ing co~ apse Su.th fire Carcinogcrts / mutagens / paiho Civil disturbance or riot Cyclone / hurricane / typhooe Dam colLapse/overliow Dese rt~ Ecalion brought Drugs Earthcpiake ticonctrnic recession I deprcssion Flee crornagnflic radiation Epidemic human (eg AI]~)S, ma!aria; animal eg That andmouth. rrthjcs) plant (eg dietiactO Erosion soil ‘ co~sLa] Fir-c (rcs]dernlal. oflice. factory) flood Fog Frost I ex(rern~ cold / ~ea ice Hcawave Indasinal accident / explosion Landslide / rockfall / mudhlow Mine accident Nuclear hazards • war • power S~floi accident Oil sptlL Orone depleE~on Plague animal (çg rabbit. [1tOLI~C) insect (eg locusi, sIre~ wasp) • plant teg prickly pear) Polluiion (water, air or land) + chemicaL + + loxic waste gas Resource shoriage Idcpleñcm Salinauort Sea level rLNC Severe staI’m a electnea! fltghtrun~) + cxtrfltte wmcl • •orreriiiat rain large hen Storm surge Subsidence Tenon sifi Inns pen accidern • ;iir • road • sea Tornado / walerspout Tsunami Uu]uy Iaiilure • power • pipelinc burst (gas/oiL) waLer + commi~nhcation • gas/fuel Volcano Warfare • nuclear • them tcal / biological Section 1 An Introduction to Hazards and Disasters 5 Classifying Hazards (contd) A ctiv i ties I a Would you classify the hazard shown in Figure 1 as geological, geomorphological, atmospheric or biological ? Give reasons for your answer. How might human acfivity have contributed to the hazard? c In 1963, a minor earth tremor set off a rockslide into the Vaiont Dam in northern Italy. The rockstide caused a huge wave of water to overflow the dam wall and flood the valley below. Almost 2000 people drowned. How would you classify this disaster? 2 Using the list in Figure 2 complete the following: a Find out the meanings of any hazards listed which you are not familiar with. b Add any others that you can think of to the list in the spaces provided. c Complete the table below, by classifying the hazards in your complete list under the appropriate headings. d Did you have trouble fitting any of the hazards into the table? If so, which ones? Explain why they were difficult to classify. Natural Hazardsgeological geomoi-pliological atmospheric biological Human-CausedHazards eg Volcano eg Flood eg Drought eg Bushfire eg Oil spill Section 1 An Introduction to Hazards and Disasters 6 Find-a-word: Hazards and Disasters ~4j3~TK1LAN C~HE JO1I~SOR~E Lu~JTENoIJTuJ~AYEG~RU S~TN PE1M~A Lii B JfG H R~D~O E1OM 0I1± EKP4!~kQ AUJEYfl QAA ~J~JJ~WILAJ~.kS~ AJ~i~ I1!~N SP~I ULM cAB 0GS LUU SEI HEV 0EU CVS KEE RLV ~ç‘A L 0 Y~W~RAOTEEB Mi U NAV LL AG RI AL RC EE TN H C I0 R0 ~J~N1VI!RPIEfl E~AA C 0 N~jI G1Y~J~D U S TaI~I2 B~A~R TNO S T~P Y~LAI~ P ARIG 0 M SH- ~JQI~L!~ILI±Lk4.xIT_‘~Lfl!~iAN!±~JJ~T S SM4:II~kJil1!~~SUBS_IDENC±Lmo~KLIc SENoC MSA~BI A! NUE TTR2! S00M~ EROY L A1 C A!~X4MLQ~$ FVNI~ DAN!P N~C~~P I E S 0 R 0 UG H T V !~R P.~0 ~N~NT AIS ,—~-lilt!Mi’A.~KLI A -i±2114HE -~!M -PIIA 1±EX IAC GL 4~LAJO;N W!jREE~E SN !CA UC !EB Complete the following and then check your answers by finding them in the puzzle above. Words are hidden forwards, backwards and diagonally. 1 A mass of snow or ice that moves rapidly down the side of a mountain 2 A serious shortage of food often caused by prolonged drought:_______ 3 Collapseofthelandsurface____________ 4 The Salvation — — — is a well known volunteer organisation which often assists disaster victims 5 An air pollutant made up of a mixture of smoke and fog: — — — — 6 activityismostcommon along the plate margins of the earth. 7 A period of prolonged hot weather:_________ S A large infestation of pests._______ 9 Bushfires burnt very close to this capital city in 1967 — 10 Material is ejected from a during an eruption. 11 This is a major form of land degradation (2 words): 12 This cyclone struck Darwin on Christmas Day, 1974: 13 Violent storm characterised by a funnel-shape and extremely powerful winds-________ 14 may pollute the coastline and kill coastal birds and animals (2 words). 15 A tropical cyclone is called a in North Amenca. 16 A may occur after prolonged heavy ram. 17 State Emergency Service (abbrev): — _. — 18 The depletion of this substance in the stratosphere leads to increases in UV radiation: 19 Major flooding of this important Australian river occurred in 1956: 20 A frequent and costly hazard in Australia, particularly in farming areas:________ 21 State Emegency Services are involved in_______ operations. 22 A major environmental hazard affecting air water and land: Section 1 An Introduction to Hazards and Disasters 7 Find-a-word: Hazards and Disasters (contd) 23 The south-east of Australia is particularly prone to this hazard during summer: 24 Massive wave caused by an earthquake at sea. Often wongly cailed a tidal wave: 25 A major pollution problem caused by rain mixing with pollutants in the air (2 words): 26 Salt lake in northern South Australia, which occasionally experiences major floods: — 27 A hazard which causes major destruction in hot wetregions (2 words): 28 Radioactive fallout is a major concern if an accident occurs at a power station. 29 This hazard involves the downhill movement of solid material: 30 These introduced animals are a major pest in Australia:________ 31 An north African country which has suffered terrible drought in recent decades: — 32 Australia’s worst earthquake occurred in this city in 1989: 33 Emergency Management Australia (abbrev): — 34 The — Toad is a major pest in Queensland. 35 One of the world’s most volcanically active countries: 36 These storms are often associated with heavy thunderclouds: 37 Insects which swarm in large numbers causing massive crop damage: 38 Earthquakes send out __ waves. 39 Lines of weakness in the land surface along which earthquakes occur:_______ 40 Blue-green ___ has been a major summer problem along the Murray and Darling Rivers. 41 Another major problem along the Murray River: 42 — — storms are often associated with drought. 43 __._. flooding occurs very quickly and is common in cities. 44 This capital city experienced major flooding in 1974: 45 This instrument is used to record earthquake activity:_____________ 46 As well as storing water, — — — — may also help control floods 47 Asian country which has experienced many disastrous floods, cyclones and storm surges. 48 The magnitude of an earthquake is measured on the Scale. 49 This famous European volcano showered ash on Pompeii in AD 79: 50 banks are built to hold back floodwaters. 51 A tropical cyclone is called a _ in south and east Asia. 52 Thunderstorms, tornadoes and land gales can all be classified as __ storms. 53 Rainy season in South Asia, often characterised by widespread flooding is called the 54 Hot, molten rock which flows from a volcano: 55 A storm is a large ocean wave whipped up by a tropical cyclone. 56 Australia’s areas are most prone to wildfires. 57 Water is often used to control fires in inaccessible areas. 58 Tropical cyclones are areas of intense — — — pressure. 59 In a bushfire, when cinders are spread by the wind — fires may start in new areas. 60..~.. Wednesday was a day of devastating bushfires in Victoria and South Australia. 61 In dryland farming areas, — _ — — rising to the surface may cause serious crop damage. 62 Tall, convex-shaped volcano: — — — 63 The hill or mountain formed by volcanic activity is called a 64 Hot, molten rock beneath the earth’s surface: 65 These Australian trees have fire-resistant adaptations:_________ 66 An opening in the earth’s crust through which volcanic material flows: The remaining letters make a word which describes an important strategy for helping cope with a range of hazards; Activitks I Read the two accounts of flooding in Figure L arid corn pare the floods under the following headings: • cause • Irequei%cy o duration • area all ECICtd • predictability 3 • spa~d of on set • destructive potenth~l • controllability -— .—. —- -~ - __a Flow Hazards and Disasters Vary Mi In! roth. ctg’rr to fftizards .md L]i~i~t~rer~r Two flood accounts i We had ii.a:rbed the water )-ise for mare ~ than two weeks, and .pent days strengthening the levee around the town to pvrea lifrom flood/ng However~ our effin-ts proved ~ LliEfrs!c as the flyer, fed b~ cotsflrti&atcs heavy rtz(N in she hilly. eventual/y broke through the levee and rrjshed rnui town We only had time to 8orner a few possen tons bçjbre we were evacuated by boat down the main Street’ We were flown cut of the eireo~ and cm/v returned a/Mr the water’ had firially receded. 10 thres taier. It wos the friiggesi flood the sown hod ever experienced. Evecytiwig was covered in mud or waterlogged, as the flood rpreiad ttcross the fawn and oi’er h~rndredx ofsquare kilomctrrrs of ntrrounthngfrrm/wrd While n~ lives Were lint. the damage toprcperry was enormous. 1) The ~oflfl co:tic#ed with high dde. h.~ whipping up enqrnjoxi~ waves. Within minutn the waler was lapping oar verandah arid after about quanet of an hour rt was ht4f a metre deep Msidti the house. We decided t~ make a run for 11. We rnrerrued Ia a twne she lEer about 500 met rer inland rind wairlied us ~ibout 2Oflam~y holiday homer along the shore buckled and collapsed in the sr~rgmgflood~ Our- as-to had been inuidcvcd yeveral ün~es before, but this fbod was the most dnrasratin#. 12 peopLe were drowned in the floods arid rnrnierous people were. utjc*red hvfalthig debris There wa~ nothing anyone could hove done against cJflood ivlndi s:rr.rk so qFück~v am4 with sr.chjbrce.. flgsire 1 2 SLudy Figure 2. Ccnnnient on the Following f~iture~, of the heinrd showw • Cause (you may need to researeb this) • area likely to be ~tf1ected * peed ictabthty a destmctve potentiaL HAZARD DATA Hazards (and djsastcrs) can vary in a number ot ways: * C~’~iute - they can be rISWra] or human-~ausctL Pnquency - some occLIr more often than others • Duration - some may be ovtr quickly while others go cu for brbg pernls • Speed 4 onset - sanw g~vc no warn irig *h~]c others have a krng lead-up peñid. • Area affecied - this may vary train a small area to a whole cairn Fry 01 regJofl. • Destructive potential - some caine wily minor damage white others may ca~c massive destruction or lift and propcr(v, + PredrcralMin~ - ~cmc foJ law ccrhun patterns, othns do not. • Comitrollabilii-v - humans arc: ithlc to control or moch(y the impacE of some t~azaxds, bul not others adapSfrcini Wazardi. Thsasters and $arWvaU. Natwmf Disanen Orzaithtrwon, J?92 Fltare 2: A tam~rjo at Noitmi. Wcstem Austtatia. FVY Comp1eti~ each of LEe fc’flowing sentences by tnertlng the words in brackets iii tht~ apprnprtak An JS a pln!Nralthsasle?, UIIUIe an isa Iiarman-causS disaster. (earthquake, oiJ 5p111) .4 .. .. i~ likely to /J~f mud. longer f/tail an (easthquake, droughl) WF~i!e h~rn Eons flUL9 ~wzie SOi!]2 C(ThIYCJ ot’e-r n rhry are inliketi~ ic, be able to contra! a (volcano, bushfire) While a . - . r~ Hkely to nff eel aii/y ~i small aie~i. a c-cm afJccl people ~ivcr a very wide area. {drought~ tornado). Figure 1: Dartua~e as n -esult al the Ncwcttstte carthqvakc. 989 HAZARD DATA ‘The word ~pcrcepiion~ refers to the way people ‘sce~ or ~feeE about the world aroanci ik~emm The ctudy of the pcrcepciori oF hazards therefbre ]oc~ics at the different ways Chat peopk VieW a potenlial hazard anó how this ktfluanccs cheir abi]ity to prepare. cope and respon-& there arc a number of reasons why peopk have differeet petceptioits ul hatat-ds. Foe eitainplc~ + Athisde- Sonic people are wElling to live with trw risk cr1 a major disaster, whik others are not. + Compeiirigfartan - Many people aecepi the risk of living in a pcucnaal hazard zone, because of the advantages the area otters. Know~edge - Peop]e will perceive a differently ii the risk is we’l-known. • t.iptrieiice - People’s perceptions wit} be changed once they have experienced ri niajor disaster. + /nforriia.fion - I’crception ib influenced by how much an individual knows about a parcicular hazard, • 7Vpe of hi~zard Hazard perceptkwt may be shriped by the ckffcrent characteristics cr1 individual hazards (c~ speed ofanset, desrructivc potential). • Ctccio~rn and beliefs - TraditionaL behaviors and beliefs may influence pcuple~ 1eclin~s ahoisc pariicular hazards. - The difFerent abiLities o~ i-ic-h and poor people to iup-t wjth major hazards is ~in itnport~nt influeiic~c qn hazard percept [rip. Figi-Irl! 2r Vii la~ in the Ethiopian pru~iaee irTircgay dLti~i rig the C9~5 drou~h ~cc wart i 1$PJmjrrogacr~~i to fla:arthc c~nd Thsasterj 9 Perception of Hazards .4ctiviiies 1 Study Figure 1. Prior to F7SY Newcastle h4d n~’er suffered rnEsjor earthqiuike damage. Explatn how how the perceptions that Newcastle residenls had of the earthqwri’re cisl.L might have been altered by the 1989 disaster 2 a Study Figurc 2. ~At the lime this photograph w~t~ taken ort]v sevi~n ci the village’s forty-five families remained. The rest had migrated to are~ts oi.itMck cii the drought zone. What does tills tell yott about the villagers’ perceptions of the drought hazard? b How does this compare with perceptions cii drought amongst Austnliart Ianters? c UsLng e~ampFes other than drought. explain why people in poorer Countries might perceive hnEirds dLffCrehIlV from those En richer countriec, 3 Make a List of the reasons why people continue to live in are~is where there is ~ high hazard risk. 4 Describe how the kilowEng people rnighl prrrelvt the hazard risk in their area. Give reasons for their perceptions. • An Hawaiian farmer living in a volcanically ac tive areas and Ciit-mtrtg fertile voki~nic soils.. • A Californian who lives south of San Francisco, and whose house suffered major deirnage during the 1991 San Francisco earrhquake • A Bangladeshi fanner ILving on a low-Lying silt island io the Bay of ~engal~ who lost a number of Iarrd[y ai-~d fr(encl5 in the tropical cyckine imdcoastatfiooding of 1991. • A north Sydney reskient, who, as a result of the 1994 bush fires, has adopted a range of srrategirs for preventing bu.chfire damage to theft home iri the future. • An Indonesian vilLager who believes that major volcanoes in their area are the homes of gods and spirits. * An Australian farmer facing Long-term damage to their land a~ a result ot overgrazing. conid. - Section 1 An Introduction to Hazards and Disasters 10 Hazards and Disasters in the Newspapers Complete the following steps: I Collect newspaper reports of hazards - both natural and human-caused - over a set period of time (e.g. one month). Try to use more than one newspaper if possible. 2 Record information about each hazard on the following table. Note • Two examples have been provided to help you. • When one hazard is covered over several days, only record it once on the table. • If necessary, extend the table below to cover all of the hazards reported. Section 1 An Introduction to Hazards and Disasters it Hazards and Disasters in the Newspapers (contd) 3 On the blank map of the world below show the location of each of the hazards that you have listed in your table Use a key to identify each natural hazard Group human-caused hazards into one category. eg • flood - north Queensland human-caused hazard - North Sea 5 Using your table and map, answer the following, giving reasons for your answer in each case a Which type(s) of hazards were most frequently reported? b Was most coverage given to local, national or international hazards? c Which contments/countries were given greatest coverage? Which were given least coverage? d Which hazard category - natural or human-caused - was given greatest coverage? 6 a Select two articles from your collection. Try to choose articles which come from different sources and which deal with different hazards and locations. Analyse each article under the following headings • length of article • detail of the hazard provided (eg location, cause, effects, relief operation) • type and depth of mformation (eg sensational account, human interest story, geographical explanation) • use of photographs, maps or other visual information • any other distinguishing features. b In your opinion, which of the articles was most effective in terms of (i) providmg factual information about the hazard (ii) holding the interest of the reader? Section 1 An Introduction to Hazards and Disasters 12 Research Assignment: Natural and Human-Caused Disasters Research Choose one of the following natural or human-caused disasters for detailed research • Droughts • Landslides • Bush fires • Acid rain • Floods • Oil spills • Tropical Cyclones/Hurricanes/Typhoons • Soil erosion * Earthquakes • Air pollution • Volcanoes • Water pollution Conduct your research under the following heading: • What are the causes of the disaster? • What are the effects of the disaster on (i) people, (ii) the environment, (iii) the economic structure of the community (eg agriculture, industry, transport, communications) and (iv) the social structure of the community (eg family, health care, education, law and order)? • What role do relief organisations play before, during and after the crisis? Consider voluntary, government and overseas organisations. • What prevention and mitigation measures can be taken to stop the disaster from occurring or to minimise its impact? Your research should involve the following steps. a Defining the topic Working out exactly what the topic requires you to do. b Locating infonnation Using a variety of sources (eg newspapers, books, videos, surveys, interviews) to fmd information on the topic. c Selecting infonnation Choosing only the information you need, using skills such as skimming, scanning and notetaking. d Organising information Getting notes, statistics, photographs, maps etc into a form which can assist the report writing and creative writing outlined below e Presenting your research findings See the two presentation requirements - report writing and creative writing - outlined below. Presentations should include a bibliography of information sources used. f Evaluating your efforts When you have completed all stages of your research, consider whether you achieved the original aims of the assignment and how you might have improved on your efforts. Report writing Using your research findings, write a detailed report on the disaster. This report should be suitable for publication in a newspaper or magazine. Creative writing Now complete one of the following creative writing options based on an example of the disaster you have researched. • Eyewitness account Imagine you are a reporter - write an eyewitness account of the disaster. • Interview with a survivor Write a record of an interview conducted with a survivor of the disaster. • Memoirs of a survivor Complete a piece of personal writing as if you had just survivedthe disaster. Say what happened, what you observed, how you survived and how your family and friends were affected • Diary of a disaster Write a senes of journal entries to cover your experiences leading up to, during and after the disaster. • A day in the life of a relief worker Imagine you are a relief worker during the disaster. Outline your methods of operation, the equipment and knowledge you use and the services you perform to help care for the victims of the disaster. • Poetry writing Write a poem discussing your experiences and observation during and after the disaster. Assessment Your teacher will provide you with details about how your research assignment will be assessed. Make sure you have a clear understanding of these details before proceeding. In this section 14 15 16 17 18 20 21 22 23 •Oushli re Survival and Property Protection 24 Section 2 The Bushfire Hazard Page • Bushfire~: Glossary of Key Terms • The Dushfire Risk in Australia • The Bushnre Hazard: How Does Your Area Rate? • Case Study (I): Ash Wednesday Bushfires, 1983 • Case Study (2): NSW Bushfires, 1994 • Controlling Bushfires • Word Puzzle: Bushfires • Bushfires and Natural Vegetation • Uu~hfires: Newspaper Assignment 14 Bushfires: Glossary of Key Terms Backburning: Burning of vegetation in advance of the main fire front to reduce the availability of fuel. Bushfire: An Australian term which refers to any fire occurring in the open and burning out of control. Convective burning: This occurs when very hot fires ‘feed’ on their own heat by sucking in air from all sides, and so providing added fuel. Crown fires: Bushfires which spread to the tops (or crowns) of trees. Firebreaks: Wide strips of vegetation which have been burnt to stop the advance of the main fire front by starving it of fuel. Fire-resistant adaptations: Plant characteristics which enable certain species to survive periodic burning. Forest fires : Bushfires which have the trees and undergrowth of a forest as their the principal fuel. Grass fires: Bushfires which have grass as their the principal fuel. Prescribed burning: The periodic lighting of low intensity fires in forests and woodlands to prevent excessive build-up of fuels such as twigs, leaves, bark and low vegetation. Also called ‘contolled’ or fuel reduction’ burning. Pyrophytes: Fire-loving plants (i.e plants with fire-resistant adaptations which enable them to thrive in a community which suffers periodic burning). Running crown fires : Bushfires which are driven by strong winds causing the flames to jump from the crown of one tree to the next. Spot-fires: Fires which arc ignited ahead of the main fire front by burning leaves and bark carried by the wind. Surface fires: Bushfircs which burn grass, forest litter, bushes and shrubs at ground level. Water-bombing: Fire fighting technique which uses fixed-winged aircraft and helicopters to drop water (or fire retardents) onto fires. rainforest wet eucalypt Forest _______ (including alpine areas) ~ dry eucalypt forest _______ savana woodland and grassland ~r~4 mallee scrub 1 desert and semi desert Areas subject to fires with little risk to people Areas subject to forest, grass and scrub fires of moderate risk to people I~ U Areas subject to disaster tires L ___ ____ Figure 2: Bushfire risk zones tops of trees may overlap Lrees contain flammable oils trees give off flammable vapour large amounts of leaf titter Figure 3: Features of eucalypt forest Section 2 5 The Bushfire Risk in Australia Figure 1~ Vegetation regions of Australia Activities I Using information in Figures 1 and 2 above, write a paragraph explaining the relationship between vegetation and bushfire risk in Australia. 2 How might each of the following characteristics of the south-east region of Australia also influence the risk of disastrous bushfires: • it is the most densely populated area of Australia; • its climate is characterised by cool moist winters and hot dry summers; • hot notherly winds and low humidity are common in summer; • it experiences prolonged periods of drought. 3 Figure 2 refers to areas subject to forest, grass and scrub fires. a Write a paragraph describing the possible differences between these three types of fires. Refer particularly to how they might differ in terms of their impact on people and property. b In the United States, brushfires are common. What do you think this term means? 4 a Study Figure 3. Explain how each of the features shown in the diagram make the eucalypt forest an excellent fuel for bushfires. b While eucalypts (gum trees) may bum fiercely in a bushfire, they also have manyfire -resistant adaptations. What does this mean? Try to find out at least three examples of fire-resistant adaptations common amongst eucalypts. c Many eucalypts belong to a group of plants called pyrophytes. What does this term mean? How would these areas rate? If your local area was not suitable, or if you would like to rate other areas, calculate a fire hazard rating for the following: An area of gently sloping grassland with a north westerly aspect. A single lane, sealed road connects the area with a small town about 5 km away. Fire-fighting facilities in the area are minimal, although there are adequate reserves of water available. An area of dense scrub, on steeply sloping north- facing land. A single lane track connects a house in the middle of the scrub to a sealed highway about 2 km from the house. There is a fire brigade based in the nearest town, 6 km away. Section 2 16 The Bushfire Hazard: How Does Your Area Rate? Bushflres The aim of this activity is to calculate a fire hazard rating for the area in which you live. This ratmg will help you predict the possibility of a bushfire occurring in your community. If you live in an area where there is little or no possibilaty of bushfires, you may wish to choose (i) another area you are very famihar with where there is a significant bushfire risk, or (ii) one of the examples provided in Figure 1. Complete the following steps. a Identify the area you will be rating. Work on art area of about I km2. If you are rating the site of your own (or someone else’s) home it should be located in the centre this area. b Using the score sheet below, rate your area according to the information provided. c Based on information on your score sheet, write a description of the fire hazard in your area. Say which factors contnbute most to the area being at risk, arid, if possible, what can be done about these factors to reduce the risk in the future d Comment on the effectiveness of using ftre hazard ratings in assessing bushfire risk. The Figure 1 Country Fire Authority of Victoria takes into account much more information in working out its ratings. What other factors could have been added to the list you used to give a more accurate assessment of bushfire risk? Factor Indicators Score 5~4nnt Slope - aspect (which way slope faces) north to north-west north-west to westmixed north; west to south north to westeast to south; mixed south 5432I Slope - steepness very steep (severe) steep (steep hills)moderate (rolling hills) gentle (undulating)flat (plains) 54321 Vegetation very heavy - eg dense forest heavy - eg scrub or woodlandmedium - eg open woodland/grassland sparse - eg patchy woodland/grassland very sparse - eg liule or no vegetation 54321 Road links into and out of area very poor - eg single lane, 4-wheel drive poor - eg single lane, 2-wheel drivefair - eg two lane, 2-wheel drive good - as above, very good condition excellent - eg two lane, double width 54321 Fire-fighting services available none - eg no ftre brigade, water supply etc poorfairgoodexcellent - eg close fire brigade, water etc 54321 Key to scoring and rating Points total Fire hazard rating 21-2517-2013 - 169-125-8 veryhighhighmoderatelowverylow ‘V’ I / HAZARD DATA The Impact of the Ash Wednesday Busbflres • ‘75 people died and and more than a thousand were treated for injuries; • II volunteer fire-fighters were killed; • 1,707 families lost their homes; • 552,000 hectares were burnt, including large areas of forests and grazing land; • 340,000 sheep and 18,000 cattle either died in the fires or had to be destroyed afterwards; • Hundreds of native animals, such as kangaroos, wallabies, possums and koalas, were killed; • More than 14,000 kilometres of fencing was destroyed; • 4,540 insurance claims, totalling almost $280 million, were made. Section 2 Hush fires 17 Case Study (1): Ash Wednesday I3ushfires, 1983 Conditions for disaster Drought conditions had persisted in south-eastern Australia during 1982/83. By early 1983, water supplies were low and the vegetation was tinder dry. On the 16 February,’Ash Wednesday’, hot and dry north winds from the inland gusted over South Australia and Victoria. By I l.3Oam temperatures had already climbed to 40°C and relative humidity was less than 10 per cent. Helped by these conditions, hundreds of small fires spread through forest and farming areas. With wind speeds increasing to above 80km/h by mid-afternoon, many of these grew quickly into major outbreaks, eventually resulting in the most damaging day of bushfires in Australia’s history. At the same time a cold front was approaching from the west, marking the leading edge of a mass of cooler air from the Southern Ocean (Figure 2). At about 3.3Opm this cold front passed over Adelaide and later Mt Gambier and Melbourne. Winds switched to south-westerlies, temperatures dropped rapidly and relative humidity increased. Light rains which accompanied the arrival of the cold front had little effect on the fires. However, in some areas the gusty south-westerlies caused fires to change direction and spread into new areas. Figure 1 Activities 1 From information in Figure 1 explain how (i) the 1982-83 drought and (ii) conditions on the day, contributed to the severity of the Ash Wednesday fires. 2 Using information in Figures 1 and 2: a Describe how the arrival of the cold front in Adelaide affected wind direction on Ash Wednesday. b In some places the change in wind direction helped firefighters, in others it was a hindrance. Explain why the change might have had different effects in different places. c Explain why temperatures dropped after the arrival of the cold front in Adelaide. d What is ‘relative humidity’? At 3.OOpm in Adelaide relative humidity was about 8 per cent. By 530pm it had risen above 60 per cent. How do you account for this change? e How would (i) a drop in temperature and (ii) a rise in relative humidity have affected the Ash Wednesday fires? Figure 2: Weather map, 5.OOpm 16 February; 1983 - SAsh Wednesday’. I A resident of Mt Macedon in Victoria said of Ash Wednesday that the final blow came late at night when the wind changed direction. What caused this change of wind direction? Why do you think it was described as ‘the final blow’? 3 Complete a comparitive study of Ash Wednesday and one other major bushfire in Australia’s history (e.g. ‘Black Friday’ in 1939, Hobart in 1967, NSW in 1994). In your study compare the different impact categories shown in ‘Hazard Data’ above as well as: • location and timing of the fires; climatic conditions leading up to the fires; • fuel (i.e. vegetation) conditions; • weather conditions on the day; • areas affected; • the type of relief operations mounted. Case Study (2): NSW Bushfires 1994 An Overview of the Fires...•.~ Fires in the EurcbatalJa Council area - rskcn fmrn $n~fside Liokint towards Batemans Bay Section2 - Bushjires Cs in e.arLy Janiary. coastal New South WaIts e~tperieii.ced ap extended pcri~d of extreme lire wrathcr nordu cit Sydney to the Queensland border and south cii Sydney to Bateman’s Bay. The areas primarily affected included the coastai plains and nearby ranges. More than ROt) fires stared between December 1993 ~nd January 14. 19’94. ‘I’hc total area burnt was in e~çes~ or 81)0.000 hectares. Intrusion by lire into the Sydney and nearby metopeCitan areas occurred on a scale fiUer before doctimerned. All areas burnt had been subject ~o previous wifdfift, but EEC cur before hn~A they been burnt sirnultaneous~. The hcadquancr~ of the Depanmcrit at Ruslirire Services became the Focal point of the operation arid t’csource~ were rapid]v marshalled From nary slate and terñttxy in the nation. lpteniauotia[ rescnu-ces from New Zealand were unused. Defence forces assisled in sir-ength Al the height of the campaign about 20.000 persons were deployed on suppression. life and jxopeny pr(1(ection aiid cu~~port a-cu vit!e5 Fire supprr~isioI& ol this magn;tisde has never before happened in Au,stralit Despite the extent of the rn-cs and their severity. particularly iii and neaç the large srban areas fron Royd National Park. sou(h ct Sydney, teduced Ic a flIflOclSC2Pt h~ the rrcs Sydney to the ~Iue Mountains to the Central Coast. losses were remarkably light. Tragica1]~. two civilians and two ‘dolunLeer Firefighters kM there litts, Another civilian apparenily stsffered a fatal li~an attack while anernpc-ing to protect his home 1mm r~re. About 205 prop.c!rtics. mostly in urban areas, were cotally destroyed. Many olbers suslained minor to severe damage. Much of this damage nectirred itt the extremely destructive Cctrno-Jannali fire on the aiternncn of January ~, when fire WeS4her conditions reached thetr peakS This fire caused the loss of Oftt civilija life, severe injuries to tue people and was responsible for apprwcimnte]y half of alt resictenia] losses in the cat ire c~inpaign This level of loss under cIte conthtions which prevailed i~ ~esEFnK>riy 1C’ the skill. cnura~e and unliring endeavo~irs of the many emergency services personnel ~rnd others who played a role in tile arid pro~rty protection. and fire suppress-ui ri. P/EU Kopcrberg CornmissiomE’r. Depanment of Bwthflre Serkicn, NYW Activities I Sturlv the information ~n \~ Overview of the Fircs,,..’ above~ a Describe at least two aspects of the NSW fires which werv nque in Australia’s hist’ny. b tVhal do you iuiderstarid by the term ‘fire weather conditions’ ? When did they reach their peak ~rr the NSW fires cr1 1994? ç ~kw does tI’e author account br the r~rnarkabLv [i~ht’ !os~es from the fixes? ci lhç’- follnwjn~ is a Ji~t oicharacteristks oF the Ash Wcdneglay bu,shftres ot 1983 in Vktor:a Lmd South .Australia: • lives ‘ost: 75 • tot~ii are~i burnt: ~32, 000 hectarcs • homes destroyed: 1,707 • duration oI fires: about 12 hours on Ethruarv u, i983 ‘ fire-lighters deployed. 21,000 (approx) Write a sprnjlar List for the NSW bttshftre5 oF 1991. From this evidence, write 2-3 sentences comparing the fires~ cot.. ..... and an Eyewitness Account THURSDAY, JANUARY 6 I flew into Sydney knowing that bushfires existed in the countryside of New South Wales. I could see these from the aircraft. The weather was hot and a strong northerly wind was blowing. I drove to my brothers house in the southern suburbs - part of a relatively new subdivision with plenty of native scrub and gum trees as well as river views. Most television reports discussed the growing bushfires in the countryside outside of Sydney and extending to the Blue Mountains. FRIDAY, JANUARY 7 tea-towel around our faces - cowboy style! By early afternoon the smoke was thicker and ash began to fill the air. We could hear police and fire sirens in every direction. Our neighbour told us to water the outside of the house continuously. Some people were evacuating their homes. Traffic was bumper to bumper with people evacuating or seeing how close the fire was. Our nearest shopping centre was surrounded by fire and the roads were blocked. We packed some emergency clothing, food and water for the two young children and waited. Within thirty minutes we could see gigantic flames canopy-hopping across the gully five hundred metres away. Fire crews arrived quickly and began back-burning the scrub. They did not use any water except when the flames endangered property. We were ready to evacuate, but all roads were either choked with cars or cut by fire. It all happened so quickly, so we were forced to stay in the house. The weather was still hot and windy and by lunchtime the news reports said the fire had reached the northern suburbs and a national park south of Sydney. Within a few hours the severity escalated and radio and television ran uninterrupted news reports - the northern suburbs were being evacuated, the major freeways north and south of Sydney were closed and firefighters from all over Australia were coming to assist. That same night we lost power and the telephone and we could smell smoke faintly in the air. Radio broadcasts (battery powered) indicated the safety measures people needed to take to protect life and property. The radio report at 6.OQpm said that one hundred houses in Como and Jannali had burnt within ten minutes. We could see those suburbs from where we were. That night the fires could be seen in all directions and most people in the street wanted to stay and protect their property. Most of the traffic had cleared, and we felt that if the need arose we could evacuate quickly. SUNDAY, JANUARY 9 SATURDAY, JANUARY 8 The next morning the sky was filled with smoke and took on an orange glow. My brother was unable to go to work because the fires had jumped the main roads into Sydney. We cleared the gutters of the house, blocked the gutters with towels and filled them with water. Combustible material was removed from near the house. This took a few hours to do and we could see every neighbour standing on their roof looking in every direction for signs of the fire. The confusing thing was not knowing how close (he fire was. The chap next door told us to put the garden sprinkler on the roof, close all doors and windows and remove any curtains from windows. He advised us not to wear shorts and tank tops, despite the heat. It was far safer to wear denim jeans and long-sleaved cotton shirts, a hat and a At 300am firetrucks screamed down our street and a firefighter knocked on our door. The message was ‘be ready to evacuate at a minutes notice’. A fire had surrounded a house at the end of the street. Firefighters used loudspeakers to explain that the fire was totally unpredictable in its direction and velocity. No house was necessarily safer than any other. By midday, huge amounts of scrubland had been backburned near us and the immediate danger had passed. The northerly winds had dropped and many fire crews were patrolling the area looking for spot fires and tiareups. Enver Malkic Section 2 Bush fires 19 Case Study (2): NSW Bushfires 1994 (contd) Activities (con 14) 2 Study the information in the eyewitness account above. a List the different measures mentioned in the account which were taken to reduce the risk of property damage. b What advice was provided regarding clothing to be worn? Explain the reasons for the choice of clothing made by the author. c From evidence in this account, why is it important to have a battery powered radio during the bushfire season? d What do you think is meant by ‘flames canopy-hopping across the gully’? Why would this type of fire be very difficult to control? e What is meant by ‘back burning’? Why is it done? What problemdid people who decided to evacuate their homes have to face? Why do you think most people chose to stay rather than evacuate? g How might spot-fires and flare-ups stilt occur after the main fire danger has passed? Figure 1: ht~cnb~d (Or ceflLrol1Cd~ h3lnlrLg to cLear undergrowth and L-rWLLmiSC ~iushf.re riik BUSI-WIRE CONTROL TECHNIQUES Where passible~ bailtflres ore us trally fought by many irauted vo~UnItnrs aid a cost rifprofrsskrnal fire fighters with vehicle mounted equipment (in s-iccessib/e terreiin) Ohsnvaeion is often provided by light aircraft and he&opiers. Planes may also be ised to drop ~ncendiaHes (sinallflrir-Iighizng capsules) ahead of i fire rn burn wide strips of wgetazieni and so stop the eidwnire of the moM frrnn In small btiuhfires crop dunthg aircraft usuig water or retan/ents are often effective ip raving flynn houses and facilities. 1-iclicopters with buckets I~t1 waterfrom dams, fakes and swrnrining pools and pro Wde a similar service. They are effective iii flappirig spot fires, ignited 6w wii,dhoniefirebrands, $ornelimes kilomnres ahead of the tnainfirefront This greatly assists and ~.ontribMLes to ~Jue saJity offire fighting crews, Larger aircmfi cite rarefy ~cced l,ecarire of cost, long iuirn-ar-oemd ttme~, limited water -sapplies arid qnesricirabk t~ffecxiveness. /tt large bxishfires~ bulldozers and graders are rised to create firebreokr ahead nffire-frrinrs &wk-hw-ning. w coçpurcnori with firebreaks. Asfrespienlly effective adapted from 1-r32w-ds, Disasters and Sin-viva!’. NaLiJnI Disasters Otgathsation, 1992 20 5ec~ti~n 2 — _._ - —-______ -- -- Controlling Rushfires ( I Figure 2~ WaLcr bo~nbing of a buthtkre Figure 3 Activities a Study Pigure 1. Suggest how (kl the Liming arLd (ii) the management ot this type ot bat-nLng cart nSuce the risk of the fire gettmg out of crOflLrOl, b I-low do you think prescribed burning would help reduce the impact ci a major buthhre? c Prescribed burnia~ only tends to OCCUr every 3-8 years in forest a teas but may occur more frequQntly in grassland ~tre~s. Why do you thirtk this 6 the case? d Why do you think sante cormervahorthts have coocerns about prescribed hurrnng? 2 Study figure 2. a In what t-vpe of terrain would this tn~thod of Iire-fightmg b~ most likely used? b What are .sorne of the itniitatiorm DI IS method?! c Suggest three dangers faced Iiy pU.ots involved in aen~i] firefighting @stng hehcopt~rs 3 Read the information in FigureR. a L)escribe three ways in which aiirraft assist tn the fLghting of fires. Li OuIlin~ at least Iwo advantages and two dLSaCI vantages of aerial fizelighting, whcn conipared to conventional methods. c Why might crop dusting aircraft be partiwMr~y suited to fighting small busMires? ci Explarn what is meant by windbornefirthnznds. How might they cause spot fires to start? Why cEo spot fires pose a particuLar danger for fire-fighting crews? e Two methods of creating firebreaks are described in Figure 3. Outline how each Is achieved. I Explain the function of backbnn~rrig. 21 Section 2 — Bushfires Word Puzzle: Bushfires Complete the following puzzle by answering the ques Lions below. If solved correctly, the centre column of the puzzle forms a question you would have to ask yourself if you were in the path of an approaching bushfire Clues 1 On days of high fire danger in south-eastern Australia, hot and dry are common (2 words). 2 Days of high fire danger are also characterised by low levels. 3 blankets and clothing are more fire resistant than synthetics. 4 are highly flammable Australian native trees. 5 Firesbumfaster 6 Farmers are likely to be concemed about dangers to during a grass fire. 7 ThestatesofSouthAustraliaand_________ were badly affected by the Ash Wednesday fires of 1983. 8 Special fire may be dropped from planes to fight fires in inaccessible areas. 9 The body can easily if exposed to the heat of a bushfire for a long period. 10 burningisusedtoclearleaflitter and undergrowth before the bushf ire season. 11 Theburningof cansloworeven stop the spread of a major fire. 12 provide the fuel for Australia’s most severe bushfires. 13 and radio warnings provide vital information during the bushfire season. 14 Smoke isaserioushealthriskfor fire-fighters. 15 Measures to ensure of property should be put in place before the fire season. 16 Cleaning of gutters and removing of garden rubbish are two examples of sensible bushfire 17 The state of experienced serious bushfires in February, 1967. 18 Lightning is one of the natural causes of bushfire 19 Ash was one of the worst bushfire days in Australia’s history. Vegetation and Fire in Australia A large pan of Ausiralia ha~ a scMraphyll vegetation. where the lcaveq of trees and bushes are Ieatheiy ~n texture. the dorniuiatil Lrecs of the sckropyll forest are eucalyprs but there is generally an understorey of bushes arid sIuruhi~ or various kinds. *ftaaffre, Before ~atptanx arrived in Australia. Frequent fires were ignitalF-lighthing or by Aboiigirial people using rut to imwove their food suppLy! These tires stopped plant truer from accimiulsting on forest floor& They would pmoh*Iy have been awfiwefirrs, having insufficient heat to Ixairrt crots~i fires. The euc-a~yp1 specks has beeit found to possess particular ñre-rcststant characLeristics, Many of them arc not killed by a ru-c which completely biirn~s oil the crown and ~irnatkr branches. Shoots tare ScM out Irorri the sarviving stems in the Iolkwing season after some species are burned The buds which can send out these shoots, caUS rpiroirnir bMJ,~. are along the ~1crn and protected Worn fin hyadiick layer of bark Other cucal~ypts have /ignorabers (n asses of dormant buds ,.nd (ood material) at ground level which cart produce flew shoots after severe b1rmrtg nf thr stem. Trees (rein the acacia lurnuly Oiler) ~O5SC55 fire-resistaiit seed, another c~daptatior. Sometimes the seeds lie dornuanE in the ground for many ycers and ftzn germinate Howevr. since peoplt have sertlod in areas near forests arid w&idlands, they have done their best. me trnp iircs As a result1 many timbered ~zeas mAy riot axpencace a for thirty yeats or mcnrr, By this time the plant Miter has built up coniderably ajid provides a substzrntta~ load of fueL A fire which eventually spreads into such an area con Sin more fiercely aid Will almost certainly become a crown fire Th thts Way! European scttkrrtcn of Au’iral a has resulted in frequent but small fires being suhsntutc-d for less frequent but far more daniaging outbreaks. adapted from ‘E~cu of Fire on the Nwui-cd E~net1 GTAQ, September /992 B&’fin’s 22 Section 2 Bushfires and Natural Vegetation Figure 1 Activities I Expl~un the rneanLngs of the following terms as used in Figure 1: sderophyil. epirormlc buds, ?rgnntxiber~,fire-resislant seed, plant litler. 2 Using information in Figures 1 and 2, answer the following: a Explain the difference between surface fires and crown fires. Ft Why were most fires befsre European settlement IikMy to be surface fires? c tinder what con ditiuns do you think crown fires occur? Why would they be parhcutarly cli rhcult tci control? d Explain the meaning of the foLlowing statement: In our e/Thrts to InPut &ri&~flres Wi! IIUtJe sometni;es had the oppos~Le it2bc~ 3 Complete the flow diagram, Figure 3, by writing phrases from the following hsl into the correct boxes; a frequcut burning of brisk discouraged • Ike-v wed fire to improve their food supply • build-up of undergrowth arid plaru litter • Inn inttnsity buruin~ kcpl unrkrgrowth down • wijn4 buslrjIres in Ausfralia’~~ history • 11w &~nhfire hazard WaZ5 Figure 2: A CFVnIL tire in a cuea1~x [çires( j_40- 60 U’X) years ago Aboriginaul poopic arrived in Atisoahi ._4_ I I-- + L -- I IL” 4--— --- 200 yei~u øg Eu~u~ieari stttlers arrived cn Auso~aH2 I 1 .-. . .-..-- 4 1 t_ I €-- -. I Fig~ure 3 • TELEX. TELEX. TELEX•TELEX•TELEX TELEX• TELEX•TELEX• TELEX~TELEX’ Bushfires still burning out of control. Early estimates of damage suggest 1200 houses destroyed. First reports from the scene suggest widespread devastation. So far, 57 people have been confirmed dead, including volunteer firefighters who were trapped on a dead end road. Choose one of the following roles Journalist Your job is primarily to write the article. However, you will be involved with the rest of the team in de ciding on the content of the article and in researching the topic. Sub-editor Your main job is to decide on the content of the ar ticle. You will also involve the other team members in this process. You should collect most of the back ground information for the article. You will work with the journalist in editing the final draft. Creative Editor Your main function is to layout the article in a suit able and clear manner and to provide all maps. graph ics and photographs. You should devise a title for the article and captions for all graphics. You will also be involved in finalising the content of the article and in the editing process. Section 2 Rush fires 23 Bushfires: News pa per Assignment Figure 1 Aim To work as a team, to produce a newspaper feature article describing a bushfire and its aftermath. Preparation • Collect newspaper articles and videos which describe the impact of bushfires on lives and property. Discuss these as a class. • Decide on the way you are going to complete your feature article. For example, will you complete it on a computer using desktop publishing software, or will you cut and paste text, pictures etc using scissors and glue? • Ask your teacher to prepare a series of additional telexes or faxes like the one above. These are to be released during the course of the assignment to provide new and more up-to-date information. Group activity 1 Form groups of three students. In your groups: a Collect articles from a variety of magazines and newspapers on varied topics. b Discuss the style and presentation of the articles you have collected. c Select a newspaper or magazine for which you will write your article. d Be sure you are clear about the style of writing you will use. It must be consistent with the newspaper or magazine you have chosen. 2 Each member of the team should take on one of the roles shown in Figure 2. As far as possible, choose roles to match the abilities of people in your group. Figure 2 Description of the task You are a team of journalists and you have been assigned the task of producing a feature article which examines the different effects of a bushfire. Using the information in the telex (Figure 1), the information you already have about bushfires and other articles that you find in your research, produce an article for the newspaper or magazine you have selected. Your article should be presented in the appropriate format and should include a title, byline (naming the writer of the article), graphics and pictures. Don’t forget your deadline! Adapted from ideas by Michael Rudd, Times Educational Supplement and David Pleydell, De La Salle College HAZARD DATA • Many Australian homes have been built in locations where the nsk of bushfires is high. • Those built on the side of a hilt are at greater risk than those on flat land, because fire burns with greater intensity when it travels uphill • Those built on north-facing slopes risk the most serious damage, as most major fires in south-eastern Australia are driven by hot. dry north winds. • Other factors affect the risk of bushfire damage including availability of water, nearness to wooded areas of eucalypts and the quality of transport links into and out of an area. Safe home • Build the house so the floor is as close as possible to the ground. • Avoid using synthetic materials, such as vinyl weatherboard, in construction • Box in the underfloor area with timber or bock. Use metal sheeting and corrogated iron roofing materials. A low-profile roof is safest. • Seal the bottoms of all doors with weather-stopping. • Fit metal tlywire or solid screens on the outside of windows and doors. • Cover in eaves and seal all gaps in the roof and walls. • Fit a leafless guttering system, or gutter leafguards. • Install a rooftop spnnkler system. • Locate LP gas bottles on the side of the house furthest from the likely source of fire, and make sure safety valves point away from the house. • Get all fire-fighting equipment in one convenient location - an accessible ‘fire cupboard’. Plan a refuge room on the south side of the house with external access to a paved area Here there must be a water supply, and access to fire-proof clothing and fire-fighting equipment. Safe surrounds • Plant trees at least as far away from the house as their fully grown height. • Space trees around the house to prevent a continuous canopy. Prune lower branches and etear dead material from under trees. • Create a ‘zone of protection’ around the house. e.g. - using trees as windbreaks: - creating firebreaks by clearing of surrounds and using roads and driveways, paved areas, lawns, and groundcovers to reduce bushfire fuel; - building stone or metal fences to shield the house from the heat of the fire. • Install a sprinkler system, preferably with an independent water supply (a swimming pool could be used) and petrol or deisel powered pump • Ensure farm animals are in a well cleared paddock. • Store firewood and flanunable fuels well away from the house • Make sure there are at least two ways in and out of the house site. Section 2 Bush fires 24 Bushfire Survival and Property Protection Activities 1 Usmg information in Figure 1, answer the followmg: a Explain why a bushfire-resistant house should have the following features’ • a floor which is as close as possible to the ground, with the underfloor area boxed in; • a low profile roof; • a leafless guttering system; • an accessible ‘fire-cupboard’. b Find out why the use of synthetic construction materials should be avoided. c Why should a refuge room be planned on the south side of the house7 d Explain what is meant by a ‘zone of protection’ around the house. Why do you thmk this zone is most likely to be needed on the north side of the house? 2 Figure 2 shows three possible home sites m a bushfire prone area of south-eastern Australia. Using the information in ‘Hazard Data’, (i) outline the advantages and disadvantages of each home site in terms of bushfire safety, and (ii) say which site you would choose. Figure 1: How to proiect your house and property against bushtires Figure 2: Choosing a home site in a buslifire-prone area (adapted from Dolan, C. Hazard Geography, Longman Cheshire, 1994) conid. Bushfire Survival and Property Protection (contd) Figure 3: A house in a bushfire-prone region of south-eastern Australia Activities (contd) 4 Either a Guidelines for housing developments in bushif re-prone areas • Avoid narrow and dead end roads. • Separate property feoces from hushland with cleared land. • Provide direct access to fires in the surrounding bush. • Make sure firefighting vehicles can enter aiid leave buildings in a forward direction. • Use natural firebreaks, such as rivers, to separate housing from bushland. • Make sure that there is an adequate and accessible water supply for all residents. • Establish a community refuge. Figure 4 Section 2 Bush fires 25 3 Figure 3 above shows a house in a bushfire-prone area of south-eastern Australia. Using the information in Figure 2 on the previous page, add a range of bushfire protection measures to the house and its surrounds. (Note: You may wish to add extra features such as roads and paths, outbuildings, trees, fences etc to your diagram). Using the ‘Safe surrounds’ section of Figure 2 to help you, design a farm property layout which reduces the potential impact of a bushfire. Draw up your design on a large sheet of paper. It should include the following: • farm house (the location of the house is important here, rather than its design) • open garage • petrol storage tanks • swimming pool • sheds • stockyards • fences and windbreaks • haystack • dam and other water sources. Label your farm property layout with as much detail as possible, indicating the precautions that have been taken to reduce bushfire impact. or b Design the layout of a new housing development in a heavily wooded bushfire-prone area. Figure 4 provides some guidelines to help you. Draw up your design on a large sheet of paper. It should include the following: • up to 50 houses • fire station • church • hotel • bushland, parks and gardens • roads and other transport links. Label your design with as much detail as possible, indicating the features which have been included to reduce bushf ire impact. Section 2 Bush fires 26 Bushfire Survival and Property Protection (contd) Activities (contd) 5 In this activity you will prepare a bushfire survival plan for one of the following: • your own home, if it is in an area of high bushfi.re risk, or • the home of a friend or relative, in a bushfire-prone area, or • an imaginary home, in a bushfire-prone area of your state/territory. a Imagine that it is the beginning of the bushfire season. Your household must decide whether to stay or evacuate in the event of a major fire. To make this most important planning decision, look carefully at each of the considerations in the ‘Stay or evacuate?’ section of Figure 5. b Imagine that a major fire is approaching your home. If you those to stay, complete your plan under the following headings, using Figure 5 to help you: • List of clothing required for all household members. • Actions that will be taken as the fire approaches. • Actions that will be taken when the fire arrives. • Equipment required to (i) make preparations as the fire approaches and (ii) fight the fire when it arrives. • Identification of room where people will shelter during the fire. • Outline of actions after the fire passes. • Special instructions for individual household members (eg division of tasks). If you chose to evacuate, complete your plan under the following headings: • The place you will evacuate to and the reasons why you chose this place as a refuge. A second choice of refuge, in case the first cannot be reached. • The escape route you will take, and, in case this route becomes blocked, any available alternative routes (a map showing your evacuation routes may be useful here). • Time of departure in relation to the advancing fire front. • A list of the things you will take with you. • A contingency plan in case members of your household are separated e.g. if children are at school when the fire threatens. • Special instructions for individual household members (eg division of tasks). Bushfire Survival Guide Stay or evacuate? The first decision to make in the event of a major bushfire is whether you and your family will stay in your home or whether you will evacuate to a safer area. In making your decision consider the following: • the improved chance of your home surviving if you are there to extinguish small outbreaks around the house; • the increased risk to very young, old, sick or disabled members of your family if you stay; • the amount of fuel reduction work that has been done around your home; • your access to basic fire-fighting equipment; • the condition and accessibility of roads into and out of your property; • the extent and reliability of your water supplies. If you feel confident about all of these factors, you will probably decide to stay. If you decide on evacuation, it should not be delayed. When the fire approaches Having made the decision to stay with the family home, when a fire approaches a number of things can still be done to reduce the risk of damage to life and property. • Telephone the bushfire brigade. • Dress in woollen clothes, solid shoes and a hat. • Plug downpipes and then fill gutters with water. • Close all windows and doors. • Fill the bath with water and soak wet towels to place in any gaps, such as under doors. • Take down all curtains and push furniture away from windows. • Fill buckets with water ready to use in putting out spot fires. • Hose down all areas on the side of the house facing the firefront. • Listen to the ri’dio for local information. When the fire arrives There will be a shower of sparks and embers before the main fire front approaches. You should also expect strong winds, loud noise and heavy smoke, which will reduce visibility. When the fire front reaches you: • stay indoors where the walls of your house will protect you from the radiant heat of the fire; • keep a watch for any outbreaks of fire, particularly on or under the roof, under the floor or where sparks can get through windows and vents; • take a wool blanket with you for cover and protection, if you are forced out of doors while the fire is passing; • drink plenty of water to prevent dehydration. After the fire has passed As soon as possible after the fire has passed, go outside to inspect for spot fires. Hose down the house, paying particular attention to the roof and underfloor areas. The air will still be very hot, so wear protective clothing and goggles, and breath through a wet towel. Extinguish spot fires as embers continue to fall. adapted from ‘Hazards, Disasters and Survival’, Natural Disasters Organisation, 1992 Figure 5: Bushfire survival guide In this section Page 2S 29 30 31 32 34 37 39 40 27 Section 3 The Flood Hazard • Floods: Glossary of Key Terms • Types of Flooding • The Causes of Flooding • The Destructive Effects of Floods • Case Study: The ‘Great Floods’ of 1990 • Controlling Floods • Case Study: Bangladesh • Flood Survival and Property Protection • Flood Cro5sword 28 Floods: Glossary of Key Terms Barrages: Structures built across rivers to control and regulate flow. Channel modification: The deepening and/or widening of a river, and the removal of obstructions, so that the river can flow more freely and be less likely to flood. Evapotranspiration: The release of water vapour from the earth’s surface by evaporation (from free water surfaces) and transpiration (from plants). Flash-floods: Floods characterised by an extremely rapid rise in water level usually resulting from short, intense bursts of rainfall (e.g as a result of a thunderstorm). Floodplain: A plan, bordering a river, which has been formed from deposits of sediment carried down by the river. Floodplain zoning: A method of flood protection which involves the prohibiting or restricting of certain land uses in areas where the flood risk is high. Flood-proofing: Building construction measures which help prevent floodwaters from entering properties. Groundwater: Water held underground in soil and rock. Groundwater flow: The downslope movent of water deep below the soil surface. Infiltration: The process of water soaking into rocks and soil. Levees: In flood protection, human-made banks flanking a river which are designed to confine floodwater to the part of the floodplain where it will cause least damage. Precipitation: The deposits of water, in either liquid or solid form, which reach the earth from the atmosphere. Rapid-onset floods: Floods characterised by a rapid rise in water level, often occurring where rivers flow rapidly through narrow valleys. River diversion: Channelling of a river in a different direction to reduce the risk of flooding and flood damage. Run-off: The downhill movement of water on the ground surface. Slow-onset floods: Floods characterised by the slow rise and fall of water level (over a period of weeks or even months). Common where rivers flow across lowland areas. Throughfiow: The movement downslope of water below the soil surface Water cycle: The circulation of water from sea, to atmosphere, to land and back to sea, and its transformation between the gaseous, liquid and solid forms. Fi~rr I _ HAZARD DATA Floods ~an be dwisfied according to t1w ~spcecL at sliich ftoodwatei-s rise. They i’a~I ~ato three categories: • Slosonsci flix,ds~ FLooding cii riven in Irw-lythg aMas, surh as cerdral md western NSW and QucensLacE. ~ well as northern Sowh Auinlia and parts of Western AttsrraIia~ nuy last Far weeks in rnortihs. floods in these areas can Ii~ad to major losses of siock and damage to crops al well as extensivc dama2e in rowl and rail links, • Rapid-onset floodv flooding occurs mare quickly in the mouwain lieadwarer areas o~ larger rivers as we]l as in the ri’~ers dta~nirn~ to Athiralias east eoast~ The ground hitre is steeper and so r]veI-s drain more quickly. Flooding may thereforc only last far çac o~ two day. These floods are potcnti&Ly much more damaging to ILte and pi~opony ~inee tti~t~ L5 generaLLy much ]css time to take preventative ac~ ion. • }1a~h~floodst Fltislt-flooding rcstdts from relatively sbor-t. miense bursts of rainfall, often as a result ol thunderstorm iclivixy This typc of ftocxhng posas the greate~u threat to loss of life and can result tn sign ificam damage io property and major soemi di~niption Flash-floods tire a serious probLem in ciics where dniriag~ systems are unabtc to cop-C Storms and c~cIones. tpecia]Iy in northern i-¼usrrallL can cause vast areas ~o flood Damage may be hmitad to propery and crock 10sse5. hut i~ annie of the most sevnc castS, human ]~k may be lost through drowning or fatal injunes susLaIne(! by ~eple can~ht in flash-11c4s F.gtirc 2 athqned front Wo~ards Thscxiferx and S~niv&t’, Nai~irth Disiisrcri Orga-nF.~alwi1. 1992 Figure 3 29 Secuion 3 -rfl~* Types of Flooding Activities 1~ 2 ~nd 3- shown as skw-wtccl. In each case gin-~ 1 .Stuclv the photographs. Figures a Classify each ox the scenes mpftI—oulset orC~ih—floo&ng, re~isoris ior yci~n aoswer~ Ii Which of the floods s likely to have brought long- term bene his to the are a affected? What beneifts might it have brought? c Choose one cii the photographs. and use ~{ as the basis for a short newspapc~r re-port Your report should indicate 11w conditions leading up to the flood. its speed of onset and the damage that i~ cause~d. Z Why might dan-i~çe to road ~nd rail links he particularly important in those area.~ 0! Australia which experience :dow-cinsei ficiods? 4 Suggc~st at 1045t twp reMons why most like lv ki occur in city Are~IS (lath-flooding is 3 Wily are rap id-ortret floods [~kely in (i) the headwater region 5 O~ ina~or rivers and ([il rivrrs drannrz ui ~ east cuast? 5 a Explain how ftopitaF cvckwtes cart cause flooding. b Apart from cvclonis. na rue two other natura’ haiarcls which can be lmked to flooding. Exp{aui the link ~n e~vch cAse, Figure 1: The water cycle in the drainage basin of a river • Heavy rain - Rapid downpours associated with thunderstorms and prolonged heavy rainfall (particularly in the catchments of rivers) commonly lead to flooding. • Dam bursts - The failure of a dam wall can cause rapid and devastating floods to people living in the valley below. • Tsunamis - These large ocean waves caused by earthquakes and volcanoes at sea can swamp coastal areas. • Storm surges - Whipped up by tropical cyclones, these ocean waves can cause serious damage to coastal areas. • Deforestation - The loss of vegetation on slopes can lead to more rapid mn-off into rivers and so increase the risk of flooding. • Snowmelt - When heavy accumulations of snow melt rapidly, the additional water supply to rivers may cause them to overflow their banks. • Deposition of silt - Where rivers have been made more shallow by heavy silt deposits flooding is more likely. • Global warming It is suggested that an increase in ‘the greenhouse effect’ may lead to global warming, which in turn may expand ocean waters and cause widespread coastal flooding. Figure 2: Some causes of flooding Section 3 Floods 30 The Causes of Flooding Activities 1 a Find out the meanings of each of the following processes shown in Figure 1: water cycle, groundwater flow, through/low, run-off evapotranspiration, infiltration, precipitation. b Using Figure 1 to help you, insert each of these words into the gaps in the paragraph which follows: groundwater, drainage,floodplains, through/low, atmosphere, infiltration, run-off, flooding, volume. Floods most often result from the overflow of rivers onto their The of water in a river depends on the amount of precipitation which falls onto the river’s basin. This water may be returned to the by the process of evapotranspiration, soak into the ground as a result of or flow over the land as Water which soaks into the ground may move through the soil either close to the surface as or much deeper as flow eventually contributing to a rise in river level and possible 2 Study the information in Figure 2: a Classify the causes of flooding shown as either (i) natural or (ii) result of human activity. Which causes were difficult to classify? Explain your answer. b Which of the causes shown might lead to a river overflowing its banks? c List three possible causes of coastal flooding. d Explain how deforestation can contribute to flooding. How might deforestation also be linked to excessive silt being deposited in rivers? e Explain how flooding can be linked to each of the following hazards: • soil erosion • earthquakes • tropical cyclones • air pollution by ‘greenhouse gases’. FLOODS: Causes of destruction and places most at risk Inundation and the sheer weight and pressure of rapidly flowing water are major agents of destruction. Currents and turbulent water can knock down and drown people and animals in relatively shallow depths. Debris carried by the water can also cause injury and destruction. Buildings are damaged by the undermining of foundations. Mud, oil and other pollutants carried by the water can ruin crops , damage building contents and contaminate water supplies. Sewerage systems may be destroyed and diseases may be spread by the floodwaters. Saturation of soils may cause landslides or subsidence (collapsing of the ground). For river flooding, anything located within the floodplain is at risk. If flooding is caused by tsunamis or storm surges, coastal areas will suffer most damage. Underground buildings and basements, buildings made of earth or constructed using water-soluble mortar and buildings with shallow foundations or with weak resistance to the impact of water against their walls, are all vulnerable to flood damage. Utilities such as power, gas and water supply are also at risk. Machinery and electronics may suffer damage resulting in communications failures and economic losses for industry. Fishing and other maritime industries may be particularly badly affected. Food stocks may be damaged by floodwaters and depleted by the losses of penned/confined livestock and damage to crops. Sites and artifacts of cultural and historical significance may also be damaged or lost. Section 3 Floods 31 The Destructive Effects of Floods Figure 1 Ac tivi ties Fill in the blanks in the following sentences using information in Figure 1. Check your answers by finding them in the puzzle on the right. 1 A major cause of death during a flood is 2 Two of the pollutants which may be carried by floodwaters are and 3 and water can knock down and drown people and animals. 4 The carried by floodwaters can cause damage and injury. 5 Buildingswithshallow walls, water-soluble or constructed of are all at risk of flood damage. 6 If systemsaredamaged,______ supplies may become contaminated and the spread of may follow. 7 The ofsoilmayleadto and subsidence. 8 Placeslocatedwithinthe of rivers are particularly vulnerable to flood damage. 9 supplies may be cut off during flooding. 10 Food supplies may be depleted by losses of livestock and damage to 11 Drowning may still occur, even though the of floodwaters is relatively shallow. 12 Thelossof artifactsisonetypeof flood damage which cannot be repaired. ~ii~U C!S U~0 R1~!OrEA N~TJS!F!A I R SAT 0ILL C!L R E R W N E R S B U A A B W I R N S T HI E R R N U E A~ E E I H I~ D A U D Li~TF RAGI&L R~T D D~N NE 1~AM1I9if~I~YEAKrTL C RO!!~SA HööTiiNti~ i Ti0N~ TiUCi~ SIIDI ‘~ ~I~J1~Pi P ~i ! !i 13 The industry may be particularly badly affected by flooding. The remaining letters form a word which desribes the areas most affected by floods caused by tsunamis or storm surges. — —. I flgurr ~: Map showing the ~xwnL of t]aods in eastern Australia. April/May 1990 Summary ot the disaster The ApriwMay 1990 floods iii caflern Australia were hugc~ They covered more than one rrulLion square kFlopiesofQueeoskiriday&clNewSouth Waks anda smaller area of Victoria (in a sepnTe ~xutme flood). Fü~ute I shows thc eMent of the floods - an area as as Franc& Cwtvn . In cernral-noufwrn NSW and centra~-inuthem Quetnstarid eontirnial, hea’~y raMs panty e.ic~set~ by cyc]crnes! dreached the flat in kind plaint Theu further wrrcntia[ rain created instant floods- Many rivers had aI~eody hoen flooded once awl were En flood again at evtn hi~frter levels, Effecs - In hoch suites, road and cai] flnks were severed for tong periods. Towns were invaded by fl~x~dwaiers and many communities were isolatecL Nj~ngan ii~ NSW and CharIei~i]k in Qucca~land (Figure 2) were particularly badly af{èued. In these two towns most residents were evacirnied by air as more ihan 2,CKX) homes and public huFEdin~s suffered serious damage Gra2iers iaccd a grim submergence uf entire properties from river cverl2ows, while stock deaths ci up to One mi}Iion were estimated. Eirtergenoy services wero stretched to the limit to provide es~ernial relief. Cost - i]~e Great Floods of L990 c]ajmeij si~~ lives and cosi the counfry a total of appmsimately $350 minion, !no~t çti which was unable :o be insured. Figure 1: Cli~rLr~ lie ]fl floo& 1990 }‘j~urc 4~ D~Iive ring cmergcr~cy siua fodder durIng - the 1990 ~1{,fl(J~ in NISW Section 3 Flood.c 32 Case Study: The ‘Great F/oods’ of 1990 Activities I Study the scenes in Figures 2 and ~. Inutg±ne Lhat you were a re5ident ci Chtirleville at the time of the 1990 floods. ThU the story of your expeñextces~ including yoL~r evacuahori from the town and yOUT ‘turn home. 2 Study the scene in Figure 1. List at 1e~st four problems farmers in f1ood-affecti~d areas would have faced cit Lnng and after the !9~CI floods. 3 a Some redd~rits ol Nyngan waited for 5CVCtdI months bef~rt~ authorities allowed thorn to reLurn LO their homes Why do you think this wa~ the ease? b One ~Ow-nalist commented that the Nyngart floods will kat’c their physicul aS psyc3wlogi cat nwittlr iIL~riN to c.:~me. What do you think the jourrt4llst meant by this corn rrtenl? CO~2Id a. Date DischargeMIJday# 15 8000 16 11000 17 14000 18 31500 19 49500 0 20 67000 g— 2122 6000063500 :~i 23 76000 b~ 24 180000 4: 25 129000 26 85000 27 58000 28 42500 29 33 500 30 27000 0~ 12 1900016000 ‘.~‘ 34 110008500 ~51 5 7500 b. 200000- 150000 to 100000 -C U C,, 50000 0• I I i ~I I I IS 16 17 15 19 20 21 22 23 24 25 26 27 28 29 30 I 2 3 4 5 APRIL MAY # ‘Discharge’ is the volume of water passing a given point in a given time. This is normally measured in megalitres per day (MI/day.) I megalitre = 1000 litres * River ‘height’ refers to the height of the water surface, measured using a graduated gauge. Section 3 Floods 33 Case Study: The ‘Great Floods’ of 1999 (contd) 4 a Using the axes provided in Figure Sb above, graph the discharge levels for the Bogan River at Nyngan shown in Figure 5a. (The graph you have drawn is called a ‘flood hydrograph’) b The ‘Summary of the Disaster’ on the previous page refers to rivers reaching two flood peaks during this period. Is this evident from your hydrograph? If so, when did the peaks occur? c Work on building up the levee banks around Nyngan was abandoned late on April 23, and an evacuation plan was put into place. From the discharge pattern shown in your hydrograph, why do you think (i) the levee work was abandoned and (ii) planned evacuation did not commence earlier? Figure 5: a Discharge readings for Bogan River at Nyngan, NSW, April and May 1990 b Flood hydrograph for Bogan River at Nyngan d Most of the rain which produced the Nyngan floods fell in the catchment of the Bogan River from April 8-14, with some additional falls from April 18-22. How do you account for the river only reaching its peak discharge on April 24? e In the period shown on your hydrograph, the Bogan River rose from a height* of about 3.5 metres on April 15, to a peak height of 5.23 metres on April 24. How do you account for a height increase of less than 70 per cent, when river discharge increased by more than 2,000 per cent for the same period? f Dandoola, a gauge station on the Bogan River upstrem from Nygan recorded a greater peak height but a lower peak discharge than Nyngan. How do you account for this? Figure 1: Ways of reducing the impact of flooding (Dolan. C. Hazard Geography, Len gman Cheshire, 1994) Some measures for flood-proofing of buildings • Shutters to prevent entry of floodwaters • Construction on elevated stilts. • Building of levee banks around building. • Use of flood-resistant materials. • Construction of water-proof walls around building. • Using compacted fill to raise level of building foundations. • Installation of a drainage sump and pump for disposal of sewage during flooding. Figure 2 conEd Section 3 Floods 34 Controlling Floods Activities Study Figure 1. a Explain what is meant by each of the following, and how each works to help prevent flooding: levees, river diversion, channel mothfication, barrages and locks. b How do dams in the upstream areas of rivers help to control downstream flooding? What problems might result from relying on dams for flood control? c Catchment treatment involves making changes in the catchnient area of a river to reduce the volume and speed of water flowing into the river. What is the ‘catchment area’ of a river? What changes could be made to a catchment area to reduce flooding? d What part do you think each of the following might play in flood forecasting: • satellite photographs and weather maps • soil moisture measurements • past records of flooding in an area. e Why do you think only a small portion of insurance policies in Australia cover loss or damage by floods? f Following a flood, what actions would be involved in post-disaster relief ? 2 Study Figure 2, which lists flood-proof features which can be incorporated into the design of buildings. Design a house, which has a range of flood-proof features. On your design: • label all of the flood-proof features; • describe how each feature is intended to work; • show the flood level against which these features will offer protection; • describe the type of flooding which the features are designed to counter (e.g. river or coastal flooding, slow-onset or rapid-onset floods). Zone 3 Zone 2 Zone 1 ~----~~- ---—-S —01-4 —-___ Outer limit of flood danger. Flood prone, Flood- Severe flood danger. All Few development restrictions protection measures further development required prohibited flood level 50 year Section 3 —~ Floods 35 Controlling Floods (contd) Activities (contd) 3 Figure 3 shows an example of floodplain zoning, a method used by local govemments to prohibit certain land uses in flood-prone areas. a The flood levels shown on the diagram indicate ‘retum periods’ for floods of certain heights. Explain what this means. b In which of the zones would you locate each of the following functions. Give a reason for your answer in each case. • A new housing development. • A linear park following the river. • A factory with flood-proof features. c In Zone 2 incentives are likely to be offered to Figure 3: An example of floodplain zoning (Dolan, C. Hazard Geography, Longman Cheshire, 1994) attract ‘low impact’ functions. Explain what functions these might be. d In Zone 1, what could be done to protect existing developments (e.g. houses, factories) against flooding? What essential waterfront activities would need to remain in this zone? e Why do you think floodplain zoning would be difficult to enforce in major cities and towns? 4 Complete the puzzle on the left using the clues below. If solved correctly the centre column forms the name of a famous flood control structure. Clues I Public is essential if people are to understand how to reduce the impact of flooding 2 A canbe the most damaging flood because it occurs so quickly (2 words). 3 by boat or by air is a common emergency procedure in a major flood. 4 The , Australia’s biggest river, suffered a major flood in 1956 (2 words). 5 Dams offer against flooding. 6 are largeocean waves, whipped up by tropical cyclones, which can cause serious coastal flooding (2 words). 7 provide protection against river flooding by holding out flood-waters (2 words). 8 Flood helps people anticipate the impact of flooding. 9 Flood can help offset the cost of flood damage. 10 ~.., such as those on the River Murray, help control the flow of rivers. 11 is one of Australia’s most flood-prone capital cities. 12 Channel allows rivers to be redirected away from flood prone areas. 13 ofthesoilleadstomorerun-off, increasing the risk of flooding. could Where diii the flwds Flood protection in Nyngan anti Warren: a comparitive study When? The town of Nyngan on the Began River. New South Wales April 1990 ExLcIin~ flood The town of Waren. abo~n 65 1cm from Nyngai~ Oc~ the Macquarie River, A Levee bank a nic ire higher than the highest flood Level ever recorded in Nyngan Z]ulTcyfflldei the town on three sides, August 1990 Muon taken before and duriog the Nyngan. Levee hanks similar to ihose protecting Raising and sirengthcr&ing of the exisiin~ kvcesby fllLin~ and stacking 300000 sandbags over the pniod of a wttk, + Establishment of groups tc> handle earthwoA~, we]fai-c, m~d[a liaison. tloedhc-at rescue, levee patrol and assista7)ce to farmers. Building up of ltvee~ well before the floods1 u~’ng all availabLe machinery, and w,ih help from an army uniL Marlcing telephone poks at the Level of the predicted peak, Circulating daily information sheets on the stace of the flood- • Movi,i~ hospital patie~ils to other Lowns. Devb,i ng an evacuation plan to transport the tntire popu’ation away from ~r~fl~n • Rttaehi rig upsti-cunt igrkuhuS 1e~ees to disperse floodwaters quicker Impart of the floods: Thy lever broke and floodwaters cwept ~nio the town ($oco abow). Almosc every building was 1lc~xled and 2i00 people were evacuated, mainly by helicopler The flood caLised damage estiwnied at $50 million Evaltpation of protection: hi the end, the Wan-en levees held after they had been raised ha~f is mete and made considnbFy wjdei. The building up of the levees was helped greatly by the use of he;LVy machinery and outside cicpertisc. The NygaFi cloud provided a dear example of the dangers of adopting a narrow approach to hood proteclion In putting their faith iii unly one measure - the raising of levees with sandbags - ihe peop’e of Nyngan overlooked other preparations~ Few lifted betoligings above The reach olfiouciwaters, ito plan for evacuation was in place and little had been &ee La dtvetop local flood Warren learnt a tot Worn the Nyngan exparithce four months ear]ier Even if (hi: levees had failed it is LikeLy thai the mnului-dinicnsional response adopted by the town would have greatly reduced the impact of the flooth. infncrnataon, eq~rtise arid awareness Section 3 FIoo~1s c Explain why the ]evees at Warren were more Controlling Floods (con hi) Figure 4 Activities (ctrntTh 5 Using information in Figure 4 , answer the fol}owiii~ a Why is Nygart’s dpproach to flood cerntrot described a~ ~ni:trtow’, wh%lc Warren’s :~ described as )rntltl~dimensiunsI#? 5 One writer commented that W~rrcn#c grea±esc aiere the ~L~L~1 QfApni aS NvngaWs experience a? tJu~ trnc. How did the Nyngan e~pcrience benefit the people of Warren? effective in protecting the town than those at Nyngan. d Explain the purposes of the following strateges used in Warren: • stacking telephone poles at the tevel of the predicled Rued peak; • cir1culating daily information sheets on the slate of the [lund; • breaching upstream agdci.dfliral Levees. Figure 1; Mud Jredgea on ihc Gasig~s Rhet nen Dhaka, BcrnØade~sh. Therr job i~ t~ Jred~e mud front the ho1tcm titthc river end w~e 1 ü builcJ up the hind. HAZARD DATA Elanglacksh is prone icr flooding fat a number of çca~ons: • Much of the country lies on the huge floodplain of the Oanges~ BrahmHputra and Megh.na nvns. 70 per cent of kml is ks-s than a mcirt’~ abcnt ~ca level. with riven, lakes ~nd swamps covering I) per cent - From April to September - the Monsoon scason - wuih west winds bnng enormous arncxrnts ol r~iO w Bangladesh and to the carchments of the x-ivers which flow throQgh the country. Construction of embarikriients along m*tr rivers itt India has caused increases in the how of wOter inc~o Bangladesh. + Tropical cyc]ortes, ~i~mmor~ over tF~e Bay of Uen~al, whip up large ocean waves caElcd storm surges which Irequent-ly inundate vast areas or the coutntry~s !ow-]ying coast. Incitased (loading has also been linked Lo the clearing of trees in the Himalayas. Deforestation has increased the rate of rurt-off and the amount of silt being sent down river ~rLtO Bangladesk As a result river beds are raised and are less able to cope with the increased flow. Flooding becomes inure frequent and more devesLating. = & ‘I! — III‘ I!~ -II:~. J•l~•• F~L :\i’slJ J MEn’.! hs A’S ‘0’ N’D Section 3 -._Plcod.s 37 Case Study: Bang/adesh Activities Explain why Bangladeshis need to undertake the work ~thown in Fisure 1. As w~11 as buildthg t~p the Jand how else would ti-Us work hdp reduce flood impact? Teniperature °C Ra]nFaII mm J F M A M J I A S C) N 0 22 24 ZR ~2 32 30 29 30 31) 19 2~ 24 10 2~ 40 50 140 290 320 330 250 120 40 5 l’ottt artruwl rairthiiL 2 Bangladesh has a monsoon cbmate The table ahov~ shows temperahire arid rainfall figures for this type of climate. a Graph these figures on the axi~s provided. b Cakulate the total annual ratntall and write it Lit the box at the end of the Labke, c From the gr€~ph, in which months is seriouS flooding most likely? What E~ercentase of rainfall occurs in these months? 3 Bangladesh expedences it s most serious floods when h&atrv rains fall li-i the catchment areas of the Ganges, Brahmaputca arid Meghna rivers. a What iS rrtcaitt by ‘eatchment are~? b Using an atlas, describe the locat[ori ot the catchmeni areas (Or these three rivers. : 4 How can the cleanng of trees in the Himaliiyns be Linked to more frequent and more devastating floods in Bang ladesh? Activities (contd) Section 3 Floods 38 Case Study: Bangladesh (contd) 5 a Using an atlas, add the following to Figure 2: • The Bay of Bengal. • Dhaka. • The Ganges and Brahmaputra rivers. • India, Nepal, Burma and Tibet. • The Himalayas. • Arrows showing how storm surges move up the Bay of Bengal to strike the coast. 6 One author comn~ented that Bangladesh experiences floods ‘through both the front and back doors’. Using your atlas and the information in ‘Hazard Data’ explain what this means? 7 How might each of the following contribute to the impact of this flooding by a storm surge moving up the Bay of Bengal: • The triangular shape of the Bay of Bengal (see Figure 2). • The very high population density in the affected area - 10 million people are packed into an area smaller than the size of Tasmania. Figure 2: Bangladesh and surrounding countries The fact that many people live on alluvial islands built by deposits from the Ganges and Brahmaputra Rivers, often less than a metre above high tide level. 8 Read the following eyewitness account of a storm surge which struck Bangladesh in 1991. When it (the wind) turned around to reach the sea the water came with a booming sound. A giant wave lifted us up and we grabbed hold of a branch of a tree. Waves crashed into each other and soared upwards. The water sounded like cannons firing. My two sisters and my mother hung onto a branch of the same tree but the branch broke. I saw them taken away by the wind ant/fall into the swirling water. a How might this type of flooding differ from the freshwater flooding caused by rivers overflowing their banks? (consider factors such as speed of onset, warning time, hazardous effects,period of inundation) b What could be done to protect people against the type of flooding described in this account? Section 3 Floods 39 Flood Survival and Property Protection 2 Know your local flood history Ask your local council or State/Territory Emergency Service: What the terms major, moderate and minor flooding mean to your area and at what official river height your home becomes isolated or inundated. • Details of your local flood plan, whether you may need to evacuate and how to get to the nearest safe location Make up an emergency kit During and after a flood you will need the following: • A portable radio with fresh batteries. • Candles and waterproof matches. • Reasonable stocks of fresh water and tinned food. • A first aid kit and supplies of essential medication. • Strong shoes and rubber gloves. • A waterproof bag for clothing and valuables. • Your emergency contact numbers. 3 Act on flood warnings • Listen to your local radio and TV stations for further information. • Stack your furniture and possessions above likely flood levels, with electrical equipment on top. • Move garbage. chemicals, poisons and fuel to a high secure place. • Secure heavy objects that might cause damage. • Protect/relocate stock and equipment in commercial/ industrial premises. • If on the land move livestock to high ground. • Check your car and fill it with fuel. 4 If you need to evacuate You may be advised to evacuate by local authorities, but if you decide to leave the area of your own accord tell the police or State/Territory Emergency Service and your neighbours. Either way you should take these actions: Figure 1: Flood surviva~ and property protection Activities I The informationin Figure 1 outlines steps which should be followed in order to survive a flood and protect property from damage. Study each step carefully. a Draw a poster which illustrates one of these steps. (If you are in a large class make sure that all steps are covered equally). As well as containing the necessary information, your poster should be designed to capture people’s interest. You may wish to use a range of • Empty freezers and refrigerators. • Collect and secure your valuables, papers, photo albums and mementos. • Turn off electricity, gas and water. • Don’t forget your emergency kit. S During and after the flood If you remain in your home or when you return take these precautions: • Keep your emergency kit safe and dry. • Do not eat food which has been in contact with flood water and boil all water until supplies have been declared safe. • Don’t use gas or electrical appliances which have been flood-affected, until they have been safety- checked. • Beware of snakes and spiders which may move to drier areas in your house. • Avoid wading, even in shallow water as it may be contaminated. • Check with police for safe routes before driving anywhere and don’t enter water without checking depth and current. • Keep listening to your local radio station and heed all warnings and advice. adapted from ‘Hazards, Disasters and Survivat’, Natural Disasters Organisation, 1992 photographs, drawings or cartoons in order to do this. b When you have completed your poster, combine it with others to form a complete set of the five steps. Display each set in an appropriate place, such as your classroom, the school or community library, the town hall or the meeting place for a local emergency service organisation (e.g. the SF5, ambulance, fire service). S 4 H I I I T1 I I I jJ I~ I I I I I 9 5 S t7 10 11 :III_ ‘4 1 I I 15 19 15 20 I6 I I I I I J23 I I J24 I I 1261 i i:Ii: Across - ~_uII I I Down Section 3 Floods 40 Crossword: Floods : HE 2$ 1221 11 I - - ri i~r::: 1 River can channel floodwaters away from built up areas. 6 Huge ocean wave caused by an earthquake at sea which can cause serious coastal flooding. 7 Emergency movement of people out of a flood-affected area. 12 Banks constructed to hold out floodwaters. 13 Australia’s largest river which suffered major flooding in 1956. 14 Flood-prone country in Asia. 16 This famous river once flooded every year, providing valuable silt for Egyptian farmers. 17 Emergency may be sent to places seriously affected by flooding. 19 Australian state which suffered widespread floods in 1990. 22 Flash-flooding is most common in these large centres of population. 23 These transport links may be cut off by floodwaters. 25 The Thames protects London from major floods. 26 Rates of water increase during floods. 27 Flood- of buildings will help protect them from damage during a flood. 2 Fine material deposited by rivers. 3 After prolonged, heavy rain the soil becomes 4 Flooding is likely if prolonged, heavy rain falls in the of a river. 5 Run-off into rivers is increased by the clearing of S A plain, bordering a river, over which floodwaters spread. 9 State capital city which experienced a major flood in 1974. 10 This type of flooding occurs very quickly. 11 Australian inland lake which occassionally floods. 15 Major river in the USA which experienced serious flooding in 1993. 18 Water which runs over the ground surface after rain. 20 The amount of carried by a river increases greatly during flooding. 21 surges are whipped up by tropical cyclones and can cause serious coastal flooding. 24 These water storage structures have flood control as a secondary function. In this section 42 43 44 46 47 48 49 41 Section 4 The Severe Storm Hazard Page Severe Storms: Glossary of Key Terms • \Vhztt are ~vcre Storms? • Severe Thunderstorms • Land C ales • Case Study: Sydney, 1990 • Severe Storm Approaching! • Severe Storm Action Severe Storms: Glossary of Key Terms Hailstorms: Thunderstorms characterised by heavy and destructive falls of hail. Land gales: Gale force winds (62km/h or stronger) over the land. Lightning: An emission of electricity (accompanied by a flash of light) from cloud to cloud, or cloud to ground, resulting from the variation of electrical charge on droplets within the cloud and on the earth’s surface. Severe storms: Natural hazard which can be divided into two broad categories: severe thunderstorms and land gales. Thunderstorms: A storm in which there are strong upward currents of air, forming cumulonimbus clouds, and producing heavy rain, thunder and lightning. Tornado: Destructive, rotating storm under a funnel-shaped cloud which moves over the land in a narrow path. 42 CHARACTERISTICS OF SEVERE STORMS Severe storms can be divided into two broad categories: severe thunderstorms and land gales. Severe thunderstorms can produce flash-flooding, damaging hailstones, lightning and thunder, destructive wind gusts and tornadoes. Land gales are simply ‘gale force’ winds (62 km/h or greater) over the land. Severe storms are very localised events, not usually affecting wide areas as tropical cyclones and floods do, so their devastating impact is often under-estimated. These storms can occur anywhere in Australia and do so much more frequently than any other major hazard On average, each year severe storms are responsible for more damage (as measured by insurance costs) than tropical cyclones, earthquakes, floods or bushfires Unfortunately, storms also kill people, between five and ten deaths are caused by lightning strikes each year Deaths also occur when strong winds cause tree limbs to fall, debris to become projectiles and small boats in open water to capsize. In fact, although many people believe that tornadoes do not occur in Australia, 41 tornado-related deaths have been recorded here. adapted from ‘Severe Storms -facts, warnings and protection’, published by the Bureau of Meteorology and Emergency Management Australia Section 4 Severe Storms 43 What are Severe Storms? Figure 1 Activities Fill in the blanks in the following sentences using information in Figure 1. Check your answers by finding them in the puzzle on the right. 1 — — — — gales are one of the two broad categories of severe storms. 2 strikesareoneofthemaindangers associated with severe thunderstorms. 3 Severe storms are responsible for more damage on average each year than tropical , and 4 Severe storms often only affect a small — — — 5 Severestormsoccurmore in Australia than any other major natural 6 Jnsurance suggest that severe storms cause more damage than other natural hazards. 7 Flying can be extremely dangerous in high winds. 8 People may drown when capsize during a storm. 9 Falling may cause death, injury and property damage. 10 flooding may result from heavy — — — —. 11 — — — - stones may be associated with severe thunderstorms. 12 Manypeoplebelievethat donot occur in Australia, but they have, in fact, been responsible for a significant number of 13 Gale - winds have a speed of 62km/h or greater. 14 is produced when lightning strikes. L I G H T N I N G L H A T S E K A U Q H T R A E 0 Y L T N E U 0 E R F L R H D E B L D G E H D A N A T R U N I A S L E N A Z H F S T D A R E A D P0 AR U 0 H T L A H F T N N R F F S S L S H I E D D C I N B 0 A T S A S S E E R T 0 X C U 0 R S T R 0 E P P E B R I S N A S M S E N 0 L C Y C Figure 1~ A i~aiure Ihunderstotrrt which i~ pr4udng bea’q rani. ]igtilntng and po5-sthty bail. Section 4 44 Severe Thunderstonns a.enrea~tonIu Figure 2: 1Iøth-flu’ods in MeI~oijme aSSOCi3LcJ with i wve-re thunde~ir ‘rm~ 911 HAZARD DATA Severe tliundeSonns are defined by the Burau of Meteordogy as those which produce: - hailstottts with a dianieicr of 2cm or more; or - wind gusts of 90km/h or greater: or - flash-floods; or - destructive wind gusts or tornadoes. a Even if Lhuridcrswnns aren’t c~anjJ1ed as ‘sever& they may still cause injury and property damage thtough Lightning strikes. * Thundentomic farm when dense cold air overlics wane moist air which is less dense. This results an wang upward currents (see Figure 1) with the heat energy stored in the air and waler vapour ccmvc,-ted into wirKi and electr[cal energy. A severe thunderstonn ~wctjrs wberi the ntittosphere i~ particularly unstable, and [s characterised by complementary up- and down draughts. • Weather phenomena associated with severe thwiderstornis (see Figure 1) iriclude~ - Hea’vy rain - the intense updranght of a mature se’~ere thuriderstot-m produccs rain drops through condensation of waler vapour. Once rain drops become too large to be supported they fall. This produces heavy rain which c-an exceed 200mm per hour. causing flash-floods (Figure 2)~ - hail - hailstones farm t~ a thuaidersorm w&ai raindrops freete at high levels mad then grow sitadily in size as they are recycled through up- and down-draughtt Urdistones larger than ciickei balls have been recorded in Australia (Figure 3). - Lighiniag amid thunder - lightning S the discharge produced when differences between wound and arnwspheric electrical charges are l#rge enough to overcome the insulating effect of the air Ughttiing strokes can occur within a cloud, between clouds ot between a cloud and the gruund~ Thunder is the sound produced by the cxpCosivc expansion of air heated by ‘be lightning siroke, - Wind gusts - in a mature thundemorm. falling nun and ha2 drag surrounding air downwards. This stro~tg dawn-draught spreads out upon reaching the ground, producing cool gusty winds - Tornadoes - these rapidly cowling columns of au are the rarest srid rvlosL violent of thundersinrn hy-prcducis They dcscend in a ramniliar funnel-shape front thu ndcrs tone clouds (Figure 4}. A tornado voitex cain range Ira width from a few metres to several 1~undred rnctitt Ii u~ual!y whirls clockwise in the Southern Hernisphme and cant~ ins winds that may reach mutt than 4SOkrnIh. oct~pied from ‘Hazards, DIsa,T~rrs ~imd S~inivaV. Nafluaf Thsasrrn Orgathanmi. 1992 figure 3: F-loilsioncs collected ~ftet a severe !hmrtderstorm at 1990, BaFtaraF. ~finona. contd Figure 4: Tornado damage. Mandiirah, WA, 1993 Seet~cin 4 - .ceiere 5rorms 4S Severe Thxrnderstonus (ccnjtd) Activities 1 Study the informafton i~n ‘H~tzard Deta’and in Fisure I a How might hghtnLng strikes be linked to U) injuries to people and (ii) damage to property? b Why is heavy rain associated with severe thunderstorms? c Severe thunderstorms occur when the atmosphere is particulady unstable. What are the condAiions which lead to a par-ticularly unstable atrnnsphere? ci ~xpkm why severe thunderstonns occur m most areas of Australia wlwrt the supply of solar energy is at its greatest - ia between September and March? e ExpLain the formation of the ‘complementary up- and down-draughts~ which occur in a ma hire severe thunderstorim f Why would hailstones grow steadily in size as they are ‘recycled through up- and down-’draughts’? 2 Explain each of the tottowmg observatmoM made during a severe thunderstorms: ‘ Huge thurnler clouds hung aMwe u~, as hamlflopmc5 the size c~ golf balls crashed onto our roof s We wakhedfroni the window as ribbons of ilg4hurtg hi tip the sky, aich one foil owed almost immed/ately by a deafrning clap of thunder. ‘ The rout 71V5 dra’en aftnost horiwn~aIk~ by the s±n’ng rcinds u4mich arrampiinm’ed the storm • The wind sw~fled in a ~ightjlinnel-shaped p~zUen.. pickir!g up obftets ond Jcrniph-tg thrm 50 metres atfliy Ti was goitc a~ quick as at eQme a Study Figure 1 a Oulilne the different types oE damage this type of flooding might cause in the centre of a major Australian city’ h Why do yet. think flash-floods arc most likely to occur jr. butit-up (city) areas? 4 Study Figiarc 3 and describe at least S different types of damage which may result from hail of this sate. S a Irt 197& two people were killed near Sandon in Victoria whera a tornado lifted their cax from the side of the read and carried at 100 metres before dumping it !flto a ditck What does this Figure 5~ .sr~s voltmntaxo repear damage iCier a sevcrc thur,dcrsKi.rrn in Sydney, 199] tragedy reveal about the charactenstics of b Study Figure 4 and describe at heast 3 more types oI damage that may result from] tornado. c At least 41 tornado-related deaths have bee~n recorded itt Australit Why do yrmu think many people still believe that tornadoes do not occur pn Austraha? 4 StLLCIy Figure 5, showing a lsrge tree which has cullapsed onto a house alter a severe thu nderstcmrm. a Suggest two possible causes of the collapse of the !ree b What problems have ber~n created for the owner of the housc~? c WIiaI ~re the 515 volunteers trymg todo to repair the dam~tge~ sc-o”~ ~—6 I r-~r S~A-. 24 I _____~ ~ ____.t — HAZARD DATA • Land gales are the other category of severe storms (along with severe thunderstorms). • Land gales are simply gale force winds (62kmJh or stronger) over the land. • Land gales usually last a lot longer and affect a much wider area than thunderstorms. • Gales blow when large differences in atmospheric pressure are concentrated over a small distance. This can happen: - between deep low pressure systems and strong highs, or — near intense cold fronts. • On a weather map, land gales are indicated by isobars (lines joining places of equal air pressure) being very close together. This is called a steep pressure gradient • In the southern half of Australia, land gales generally occur in winter or spring. In the tropical north, the strongest winds usually hit in summer and autumn, and are often due to tropical cyclones. adapted from ‘Severe Storms: facts, warnings and protection’, Bureau of Meteorology and Emergency Management Australia. SA starts clean-up after damaging gales ADELAIDE: Gale-force northerly winds of up to 90km/h lashed large areas of South Aus tralia yesterday. Many parts of the state were covered in thick red dust, as winds gusted over the state’s rural interior and frustrated farmers waiting for opening rains. Near-drought conditions have occurred across most of the state this year, and the com bination of the dry, hare land surface and gale- force northerlies swept hundreds of tonnes of valuable topsoil into the atmosphere. The blanket of dust covered Adelaide, and its northern suburbs. Visibility was reduced to virtually nil, causing problems for planes ar riving at the Adelaide airport. The dust was also blamed for a series of traffic accidents, including a six-car pile-up and a level crossing collision. At the height of the gales, the Electricity Trust of South Australia were forced to dis connect power to a number of areas because of the fire risk. Such a precaution is a direct result of the disastrous Ash Wednesday bush- fires in 1983, when fires were sparked by power lines rubbing together in the strong ~v i nd s. MAY25, 1994 Section 4 Severe Sto ,ins 46 Land Gales Figure 1: Weather map on a day when land gales occurred in southern Victoria, 11 June 1993. Activities I Study Figure 1. a What evidence from the weather map suggests that southern Victoria experienced land gales on 11 June, 1993? b From which direction were winds blowing in southern Victoria at the time the weather map was drawn? How can you tell? c What other conditions was southern Victoria experiencing on 11 June, 1993? 2 Study the information in Figure 2. a Explain how land gales and drought conditions combined to produce the severe duststorm described. b What problems resulted from the dusts torm? c Why did the Electricity Trust of South Australia disconnect power to a number of areas? 3 Land gales can be particularly damaging in rural areas. Suggest some of the problems that may result from the following: • a land gale occurring in January in a fruit-growing district, specialising in stone fruits such as apricots and peaches; • a land gale occurring in a wheat growing district (i) just prior to sowing and (ii) at the time of harvesting; • a land gale occurring in winter in a sheep farming area. Figure 2 Sydney storm worst on record A STORM which cut through Sydney yesterday has been hailed as the most damaging thunderstorm ever to hit Australia. By sundown it had slashed a violent path across the city, dumping 10-centimetre hailstones and causing an estimated $360 million in damage to cars and homes. The storm came with very little warning. At 1030am the Bureau of Meteorology issued a routine forecast for Sydney, predicting ‘a shower or two and a slight chance of a thunderstorm’. Even in the early af ternoon, as the storm cell began forming, people con tinued to enjoy the sunny weekend weather. It was only at 300pm that the weather bureau, using its radar tracking system, was able to detect a rapidly growing thunderstorm. A ‘severe storm’ warning was immediately issued on the radio. The storm cell continued to grow, as towering clouds moved towards the city. Within these clouds, ice crystals were sucked higher by huge updrafts of air. They grew so big that they could not be held aloft and so plunged back to earth. As they fell, they were caught once more in the up draft and lifted again. This process continued, until by 330pm, hailstones the size of oranges were falling on Sydney’s south-western suburbs. Here they smashed through windows, tore branches and leaves from trees and left hundreds of cars pock-marked. The winds left greenery and wood scattered over roads. Roofs of houses were torn off and more than nine kilometres of powerlines were brought down. In the hard-hit western suburbs, power had still not been restored to some areas this morning. Extensive flash-flooding after heavy downpours of rain, caused building damage and cut off roads. This morning, the Riverwood Golf Course and some areas of parkland were still underwater. In all, the State Emergency Service responded to more than 4000 calls for help in Sydney’s southern and western suburbs. By the time the storm was over the northern subuTbs it had begun to weaken and less calls for help were received. The storm has insurance companies reaching for the record book, with several claiming it will be the largest payout for a natural disaster they have ever faced. One major company has predicted that the storm would end up costing them $120 million in car repairs and $35 million for home claims. MARCH 19, /990 Section 4 Severe Storms 47 Case Study: Sydney, 1990 Figure 1 Activities 1 Read the information in Figure 1. a One insurance company described the storm as ‘the worst natural disaster ever to strike New South Wales’. Comment on the accuracy of this description. b The Bureau of Meteorology were only able to provide about 30 minutes warning of the storm to some areas of Sydney. Why do you think it is difficult to provide accurate warnings well before a thunderstorm hits? What difficulties would have been caused by the short warning period in this case? c Describe the process by which ‘hailstones the size of oranges’ were formed. d Group the hazards resulting from the thunderstorm under their different causes i.e. hazards caused by (i) heavy rain, (ii) strong winds, (iii) hail. e Make up a list of at least five reasons why people may have called the State Emergency Service (SES) during and after the thunderstorm. What problems might the SES have experienced in responding to calls for assistance? 2 Write a short descriptive account based on one of the following options. • 1 was in Sydney on March 18, 7990, and this is what happened to me. • i’ve been caught in a major thunderstorm, and this is an account of my experiences. • This is what I imagine a major thunderstorm would be like. In each case, try to describe your observations, actions and feelings before, during and after the thunderstorm. HAZARD DATA • The Bureau of Meteorology is responsible for provision of warnings of dangerous weather to the Australian community, with the aim of minimising injury and damage. • The warnings are transmitted to authorities such as Police, State and Territory Emergency Services, and to radio and television stations. • Forecasters use data from satellites, radar, lightning detection networks, ground observations and computer models to prepare the warnings. • Short term warnings (up to 3 hours ahead) and longer term advtces (up to six hours ahead) areissued for severe thunderstorms (see Figure l) • Land gale warnings are issued on a district scale throughout the country. These warnings generally cover periods of six to twelve hours and are not as specific or detailed as severe thunderstorm warnings. Section 4 Severe Storms 48 Severe Storm Approaching! a. SEVERE THUNDERSTORM WARNING BUREAU OF METEOROLOGY, SYDNEY Issued 5.OOpm on Friday 26/3/93 Severe thunderstorms with severe wind gusts~ damaging hail, and very heavy rain are expected during the next hour in the following Council area: S YDNEY METROPOLITAN A LINE OF THUNDERSTORMS EXTENDING FROM JUST NORTH OF PENRITH EASTWARDS TO THE COAST AT 5PM HAS PRODUCED HAIL UP TO 2 OR 3CM IN DIAMETER AND STRONG WINDS IN SOME SUBURBS. THESE STORMS ARE EXPECTED TO PERSIST FOR AT LEAST THE NEXT HOUR. The State Emergency Service advises you to: * put your vehicle under cover; • stay inside away from windows; and • ring your local SES unit for emergency assistance if your house is damaged K SEVERE THUNDERSTORM ADVICE BUREAU OF METEOROLOGY. PERTH Issued 1245pm on Saturday 1/5/93 FOR THE INLAND PARTS OF THE WEST GASCOYNE SEVERE THUNDERSTORMS ARE POSSIBLE DURING THIS AFTERNOON AND EVENING. WIND GUSTS IN EXCESS OF 90KM/H, HAIL AND FLASH FLOODING MAY RESULT IN DAMAGE TO PROPERTY. Figure 1: a Short-term thunderstorm warning h Longer-term thunderstorm advice Activities 1 a Why do you think each of the following characteristics of severe thunderstorms make them difficult to monitor and predict: • many have a lifetime of three hours or less; • the diameters of some storms are less than 10 kilometres. b What types of technology are used by forecasters to make tracking and prediction more accurate’ c What additional problems might result from a very short warning time before a severe thunderstorm? 2 Read the mformation in Figure 1. a Why do you think the Bureau of Meteorolgy issues two types of severe thunderstorm warnings? b From the examples shown, what are the main differences between the two Wpes of warning? c List the different types of information contained in the short-term warning. Write your own short-term waming, imagining that a severe thunderstorm is only two hours away from your area. 3 Land gale warnings are tailored to meet local needs, and cover a period of six to twelve hours. Write a land gale warning for your local area containing the following informatiorr • Title. • Place of issue. • Time and date of issue. • Expected wind speed and direction. • Details of area likely to be affected. • An estimate of the times over which the gale is likely to blow. • Prediction of likely damage to crops, animals, buildings and people. • Prediction of associated hazards such as duststorms, flying debris, fallen trees and reduced visibility. SEVERE STORM SURVIVAL AND PROPERTY PROTECTION Actions before the storm season Actions as the storm approaches Actions when the storm strikes * Actions after the storm passes • If you need emergency assistance contact your StateiTerritory Emergency Service. • Trim tree branches well clear of your house. Clear loose objects from your yard. • Place vehicles under cover. • Keep clear of windows and large areas of glass. • If driving, pull over, park clear of trees, powerlines and watercourses. • Listen to your radio for storm warnings. • Shelter and secure pets and animals • Check your house for damage. • Disconnect all electrical appliances. • Clean and check roof guttering and downpipes. • Make sure you have a portable radio and torch with fresh batteries. • Listen to your radio for storm updates. • If outdoors, find emergency shelter (not under a tree). • Don’t go sightseeing, stay at home to help others. • Beware of fallen powerlines, flooded watercourses and damaged buildings and trees • If necessary, shelter under a table or cover yourself with a mattress, blanket, quilt or tarpaulin. • Tape (in an ‘x’ pattern) or cover large windows. • Ensure yuu have a first-aid kit. • Stay inside and shelter in the strongest part of the house (bathroom, cellar) and don’t use the phone. • Purchase masking tape (for windows), plastic sheeting and large garbage bags (for rain protection) • Listen to your radio and heed official advice and reports of damage and disruption to services. adapted from ‘Severe Storms Action Guide’, Emergency Management Australia. Section 4 Severe Storms 49 Severe Storm Action a. Figure 1: a ‘Severe storm survival and property protection’ b List of possible actions Activities K 1 a Complete the chart ‘Severe Storm Survival and Property Protection’ (Figure in.) by filling in the blank spaces with the actions listed in Figure lb. Share your responses as a class to check that their is agreement about when each action should be taken. b Working in small groups, plan a poster around one of the categories in your completed chart (make sure all categories are covered in the class) When your poster is completed, display it in an appropriate place along with those that other groups have produced. 2 Explain the reasons for each of the following actions: • Using masking tape in an ‘X’ pattern across windows. • Having a portable, battery powered radio. • Cleaning and checking roof guttering and downpipes. • Disconnecting all electrical appliances • Clearing up loose objects from your yard. t’O?z 51 EMERGENCY ASSISTANCE (Who and when to call) STATE/TERRITORY EMERGENCY SERVICE Call your nearest unit for emergency assistance with house damage, and/or advice about temporary accommodation, food and clothing. ELECTRICITY AUTHORITY Call your local office for power failure, fallen power lines or other electrical problems. WATER BOARD/AUTHORITY Call your nearest depot if your household water supply is damaged or interrupted. GAS COMPANY/AUTHORITY Call your local office for gas emergencies. IINSURANCE COMPANY Call immediately to arrange approved tradespeople to repair your home This is your responstbility. POLICE, FIRE, AM3ULANCE If unable to phone emergene~ services: • Listen to radio for official warrungs/advice. • Form a self-help group with family and neighbours. • Watch for emergency services crews who will check your area as soon as possible AVOID USING THE PHONE DURING STORMS. SOME FACTS AND MYTHS ABOUT LIGHTNING * Lightning poses a greater threat to individuals than almost any other natural hazard in Australia. • On average, as a result of lightning strikes, five to ten people are killed and over a 100 injured each year. • Most injuries occur when people use telephones during thundcrstorms.They may receive an electric shock, hearing damage or burns when lightning strikes the lines in their area and the phone system becomes part of a highly charged electrical circuit. • When struck, people do not glow or ‘fry to a crisp’, but the heart and breathing are often affected. • Only about 30 per cent of people struck by lighning actually die, and the incidence of long-term disability is low, particularly when first aid is applied promptly • If you apply heart massage or mouth-to mouth resuscitation to a lightning victim you do not receive a shock from the victim. • If you hear thunder 10 seconds after a lightning flash, it is only about three ktlometres away. The shurter the time, the closer the lightning • If your clothes are wet you are less likely to he seriously injured if struck, as most of the charge will conduct through your clothes rather than your body. • Lighotog often does strike the same place twice • The best places to shelter from lightning are in Shard top’ vehicles and solid buildings. Section 4 Severe Storms 50 Severe Storm Action (contd) 3 a Complete Figure 2 by entering phone numbers on the dotted lines You will find the numbers you need in your local directory under ‘all other emergencIes’ (referred to on inside cover) or by looking up the name of the specific authority or company. b When you have completed the chart, cut it out and display it in a prominent place near the telephone in your home 4 Read the information in Figure 3. a Why do you think lightning is not widely recognised as one of Australia’s most dangerous natural hazards? b What are the most common lightning-related injuries? If a person is struck directly by lightning what type of first aid is likely to be needed immediately? c What does it mean to say ‘the phone system becomes part of a highly charged electrical system’ when the lines are struck by lightning? 5 a It has been suggested that deaths and injuries from lightning strikes will increase as the Figure 2 adapted from Severe Storms Action Guide’, Emergency Mona gemen r Australia. proportion of retired people in the Australian population grows, and their participation in golf, boating and fishing increases? Explam why this might be the case. b Give reasons why each of the following actions should be avoided if lightning threatens: • flying a kite • sheltering under trees • working on a computer • taking washing off of the line. Figure 3 adapted from ‘Lightning Protection Acoon Guide, Emergency c As a class, devise a list of actions that should be ‘vtairogeoieiit ~tuwotio taken in the event of dangerous lightning. In this section 52 53 55 57 59 60 62 63 64 65 66 5] Section 5 The Tropical Cyclone Hazard Page • 1rupical Cyclones: Glossary of Key Terms • Pressure. Wind and Cyclones • Tropical Cyclones Exphined • Cyclone Approaching! • Rewa: Diary of a Tropical Cyclone • Case Study: Cyclone Tracy, Darwin, 1974 • Storm Surges • Fmergencv Management: Tropical Cyclones • Cyclone Sun’ iv a] and Property Protection • Community Responses to a Tropical Cyclone • Crossword: Tropical Cyclones 52 Tropical Cyclones: Glossary of Key Terms Anemometer: A instrument used to measure and record wind speed. Atmospheric (or air) pressure: The pressure at a certain point exerted by the weight of the ‘column’ of air above that point. Coriolis effect (or force): The deflection of winds (and any other freely moving objects) produced by the rotation of the earth on its axis. Eye: The calm area of extreme low pressure at the centre of a tropical cyclone. Eye wall: A band of heavy cloud associated with moist air which spirals around the centre of a tropical cyclone. Hectopascals: Units of measurement for atmospheric pressure. High pressure system (high, anticyclone): A region, often thousands of kilometres in diameter, in which the atmospheric pressure is high compared with that of adjacent areas and which appears on the weather map as a series of concentric widely spaced isobars. Isobars: Lines on a weather map joining places of equal atmospheric pressure. Low pressure system (low, depression, cyclone): An area of low atmospheric pressure with winds moving in a spiral around the centre of the area. Pressure gradient: The change of atmospheric pressure from one area to another. On a weather map this is indicated by the distance between isobars. Rain depression: A low pressure system over the land (or cooler water) which is the remnant of a tropical cyclone. Associated with heavy rainfall in inland areas. Storm surge: The ‘piling up’ of sea water caused by extremely low pressure conditions and strong onshore winds (thus often associated with tropical cyclones). The rapid rise in tide level resulting from a storm surge can cause serious damage to coastal areas Tropical cyclone (typhoon, hurricane): An intense low pressure system in which air moves in a large, tightening spiral around the centre. Wind: The invisible movement of air from one place to another. further lighter Figure I: Low pressure syscem in the Sou~hern Kerrusphere she wing the cifeet of pce~s~tre gradiens cm wirtd HAZARD DATA Wind js The invisih!e movement of ais- IrCfl)1 Ohic place tc~ £tnother, Atmospheric (or air) pressure is the pressure at a paLm on the earths surtacc caused by the weight of the cLlIumn of a~r abeve 1!mi point. + Atmospheric pressure v~thes from place to pt~co. • Rcpc’ns of hifl~ preMsurc are known as high pressure systems (‘highs1) ~r aalky!ones. regions of low pressure arc- known aS Low pressure systems (k’w~). depressions or cyclone, (flgure 1). • Air, in the form of wind, moves froin areas of high pressure to areas of low pressure. - The speed ci the wind depends on th~cUfference in sir prenuri~ between tw~ poüns. the greater the difFerence itt pressure the grcater the wind speed. • On a weather map, isohari are lines which connect pliice~s of equal air pressute. Air pressure i~ nwasitcd in hectopase-ak, with isobars normally drawn at iitte,vals of two hectopascals. if isoSs are close iogeiher this means the pttssurc dirference hctween Iwo points wilL be great and therefore the winds will be strong If they are a Long way apart winds will be Ighter (Figure 1), Wind speed is measured ~n kilomeires per hour ~w in knots. The instrument u~cd to measure wind speed EN an arieirjiineter (Figure 2j. • W[yids do not move ifl a sLtai~ht I ;~e~ hut insicad are de{kcted because of the rolalicin of the earth. This i~ knawn as the Coriotis Effect. • This deflection - to the left in the Southern Hemisphere and to the righi in the Northern Hemisphere - ~uses winds to circulate around h~hs arid tOws. • In the Scrudiern llemisptrere ctculzttio.i is ckickwise iii~o the ccrurc of ~i low and nritj-clockwise out from the certtre of A hig]i (Pi~uje 3!, The opposite occrlr.c in the Northern Herrtisphere. A tropical cydocie is a very severe low pressUre system ti.e where pressure gradienis an very ~ieep). Ia parts at An it ‘.s cal [cit a typhoon ahd frt Ncirth Anisrica a hurricane. a awed &tçriort5 -- Pressure, Wind and Cyclones speed Fi~vre 2: An ~ Figure 3~ PalLei-n nr wjcfr(I t~rcu1~iwin in {a~ a k~w ~ji-~ *~S(Ccn smd (hi a high pr~ssu~ sySeni u~ the So~Lhcm ]-IemispL~ere Tropkcd Cyc1orit~s CALM EYE ANTICYCLONE WEATHER MAP HIGH LOW AIR PRESSURE GRADIENT HECTOPASCALS Section 5 Tropical Cyclones 54 Pressure, Wind and Cyclones (contd) Activities I Using the information in Figure 1 and in ‘Hazard Data’ on the previous page. complete the following questions by circling the correct answer from the alternatives provided: a Which of the locations in Figure 1 has the highest air pressure? A B C D b Which of the locations in Figure 1 has the lowest air pressure? A B C D c Which of the locations in Figure 1 has an air pressure reading of 1003 hectopascals? A B C D d Which of the locations in Figure 1 is probably experiencing the highest wind speed? A B C U e Which of the locations in Figure 1 is probably experiencing the lowest wind speed? A B C U f The wind direction at location C would be: (i) northerly (ii) south-westerly (iii) westerly (iv) easterly (Figure 3 may help you with this answer) H E C T 0 P A S C A L S I N C W G R A S T 0 N K G 0 0 H A E W A E S U R H L R U L S E I S N E E T C I R E S A R I 14 P T N Y 0 14 S U T W W N R E E C L I R R H E K 0 E M I I I C A E E Z C 0 S 0 U T ! A B M 14 E 0 H S M A N C N 0 L M E L P I E R A N E S A A R C Y 0 N G E Y E I C P B I T N A g The wind direction at location A would be: (i) northerly (ii) south-westerly (iii) north-westerly (iv) easterly 2 Study Figure 2. Explain, with the help of some research if necessary, how the anemometer works. 3 Study Figure 3. a Suggest two other names for the low pressure system in Figure 3a. b How can you tell that the pressure systems shown are in the Southern Hemisphere? c Why do you think low pressure systems are sometimes called ‘zones of convergence’? d Describe what the wind conditions are probably like in the centre of the high. 4 Try the following experiment to test the Coriolis Effect. • Have a friend rotate a cicular piece of card, anchored by a drawing pi~ in the middle. • As the card is rotating try to draw a straight line with a pencil from the edge to the centre. • Stop the spinning card and study the lines you have produced. • Did you find your lines were curved rather than straight? If so, they can be be likened to the deflection of winds as they move towards the centre of a low. 5 Find the following key words from this topic hidden in the puzzle on the left: DEPRESSION CORIOLIS WIND KNOTS CLOCKWISE ANEMOMETER ISOBARS TYPHOON HURRICANE GALE BREEZE The remaining letters make up the name of an Australian city which has a high tropical cyclone risk. FIgure 1: A tropical nctenc Viewed Iwrr. space HAZARD DATA Tropical cyclones (or hurrieanm~s / typhoons) are intcrise low pressure systems rn the tropics, Mr spiraLs at speeds crxcceding l2Okm& around the cencte of these lows. like a giant whirlwin& ‘ In the Southern Hemisphere witd circulates in a clockwise dirrctiow • Winds circulate around the ey~ or centre of a tropical cvclone This is therefore arc area charttuerised by calm conditions and often cicar sides. The diameter o1 the eye c~in range from I(*m to over 100km. • flc eye is surro~rnded by a dense ring of cloud about 15km high callS the eye wall ~Figurc I). ‘[his marks thc belt of strongest winds and heaviest rainfalL • The vast amount of’ energy released from ~ tropical eyclonr is obtained from heat arid moisttice~ Tropical cyctories therefore tend to develop o’ver warm ocean walers bctwccri 50 and ltP1 from the equator. • The avenge ~lEte cycle’ of a tropical cyclone bits about seven days bun can extend up to three weeks. Ii consish~ of a number of stagcs~ i Intense s~rniinen heat beating on the warm ocean causes a core of mui~~t warm air lo rise. ii This rising air spirals outwards at upper levels, pro&icin~ conditions in v.tich air is remcveJ laster il-nan it is flowing in (Figure ~ iii This causcs a lowering of air pressure on the surface of the sea As a restiLt, the winds get stronger and the low ~r1±~tUtC intensifies L1n Lii ~ powerful tropical cyc-lone has dcvclcped. iv The rapid uplift of rrtoisl air produces huge banks of curnuicrtimhus clouds around thc eye, bringing the i~ten~e rain associaceci with tropical cycbncs. v The cyclone follows 4i Lrnck which is generally polcwand, hut may he nrutrkcd by major changes in specd ar~d direetion~ vi As a Iropical cyclone reache~s cooler wacer or land the loss of swiaircing heat cntrgy causes it to dnop mo~L of its moisture as it weakens no a rain depresslout FIgure 2: S~n5d ore at a rnipicat nil one TrcpicoI çyc1~wies nvi a! Tropical Cyclones Explained Activities I a Make as~ekh of Figure 1. On your sketch, label; the rye !~ !Jse cyclww, the eye tr.~I1. the arro of stronge.c zohi~ tucd he!virs~ Ti2iPJ,fiIU~ f~w 4irxtioi~ LIf Snd ~irccr1Jftw~, b Does Figure 1 sho~.v a tropical cyclone in the Southern Cr Northern Hemisphere? How can you teiP 2 Eicpl4in ~\‘hy the eve ol a rye lorIc! iS ~fl ~zea of (i~ cairn cnndihort~ and (ii) clear skies 3 Why do tropical cvdones knd to develop o’ier warm oc~aj-& wateet between Yand flY from the eq uaior? 4 1 leavv rain L5 always associated wLth tropical cyclctr’tes. Why is this th’ case? S Study Pigure 2. FxpEaii-t how ~iir is removed faster than it i~i flowing in. Why is this so important in tropical cvclc&ne formation? 6 Why do tropical cvcla~nes weaken when they MOW CWCr laS on coder water? 7 Wttat is a ~a~n depression’? Who might beneElt from the weakenmg of ti-upicat cycloiies as they move over land in AusLraha? Section 5 Tropical Cyclones 56 Tropical Cyclones Explained (contd) 8 Study the weather snap, Figure 3. a Suggest at least two reasons why the low pressure system south of Perth would not be considered a tropical cyclone. b Describe the air pressure, wind speed and wind direction at each of the following places: Perth, Adelaide, Sydney, Townsville, Hobart. c What is the air pressure at Port 1-ledland? Can you suggest a possible wind speed and direction for Port Hedland? Explain how you worked this out. d How are the following characteristics of tropical cyclone Damien shown on the map: • extremely strong winds close to the centre of the cyclone • extremely low air pressure in the centre of the cyclone • widespread rain associated with the cyclone. e From evidence on the map, say why the people of Alice Springs might welcome cyclone activity on the coast. f Imagine that tropical cyclone Damien is moving in a south-easterly direction at a speed of 30km/h. Explain what is likely to happen to the cyclone in the next 24 hours. 9 Complete the puzzle below using the clues provided. If solved correctly the centre column forms the name of a Western Australian city which often experiences cyclone activity. Figure 3: Weather map, 3 February 1987 Clues 1 Cyclones, hurricanes and typhoons all occur in the 2 In a tropical cyclone, these lines on a weather map will be very close together 3 Atropicalcycloneisknownasa in North America. 4 Tropical cyclones often change their speed and as they track polewards. 5 Atropicalcycloneisknownasa in parts of Asia. 6 When a tropical cyclone moves over the land, it weakens into a rain 7 As the movements of tropical cyclones are often very erratic, this makes the time and place where they will cross the coast difficult to 8 Winds aroundthecentreoreyeof a tropical cyclone. 9 The belt of strongest winds and heaviest rainfall surrounding the eye is called the________ 10 Tropical cyclones are cotnmon along the north coast of II The area surrounding the eye is characterised by very heavy (2 words). Activities Section 5 Tropical Cyclones 57 Cyclone Approaching! Answer the following using information in Figure 1, as well as your own ideas. a For Cairns, Townsville and Mackay describe the likely weather conditions at 9.OOam, January 21. (include estimated temperature, wind speed and direction, cloud cover, rainfall and air pressure). b Choosing one of these centres, describe how conditions are likely to change in the next 24 hours. Using information in Figure 2 on the next page to help you, describe the types of damage which people living in this centre might expect as cyclone Thomas approaches. c Townsville is expecting high tide at 6.2Opm on January 21 and at 5.4Sam on January 22. Figure 1: Cyclone Thomas approaching the Queensland coast How might damage be increased if either of these tide times coincides with cyclone Thomas crossing the Queensland coast? d A flood-alert has been issued for Brisbane, saying that their is a strong possibility of localised river flooding in the next 48 hours. How do you account for the likelihood of flooding in Brisbane? 2 With the help of Figures 1, 2 and 3, complete the ‘Cyclone Warning’ on the next page for cyclone Thomas by filling in the blank spaces. con! c/ Cyclone Warnings • Cyclone warnings are issued as soon as gales or stronger winds are expected to affect coastal or island communities within 24 hours • Cyclone warnings are issued every three hours, When a cyclone is under radar surveillance close to the coast and poses a severe threat, hourly advices are issued. • The strength of maximum wind gusts over particular areas are indicated in the following terms: - gales with gusts to 125km/h - destructive winds with gusts above 125km/h - very destructive winds with gusts over 170km/h • The warning may mention above normal tides. They are descrIbed as follows: - abnormally high tides could cause minor flooding - exceptionally high tides could cause serious flooding - dangerously high tides could cause inundation of low lying coastal land ) 58 Section 5 Cyclone Approaching! (contd) Tropical C’vcloner Category StrongestGust (km/h) .Typical Effects I less than 125 Negligible house damage.Damage to some crops, trees and caravans. Craft may dragmoorings 2 125-170 Msnor house damage Significant damage to signs, trees and caravans. Heavy damage to some crops Risk of power failure. Small craft may break moonngs 3 170-225 Some roof and structural damage. Some caravans destroyed. Power fatlures likely. 4 225-280 Sigificant roofing loss and structural damage. Many caravans destroyed and blown away. Dangerous airborne debns. Widespread power failures. 5 More than 280 Extremely dangerous with wsdespread destruction. Figure 2: Cyclone seventy categories Figure 3 CYCLONE WARNING: Top priority - for immediate broadcast Issued by’ Time of issue’ Name of cyclone’ Category (see Figure 2) Position of cyclone at a specified time Direction and speed of movement’ Strength of maximum wind gusts over particular areas (see Figure 3)’,,,,,,..,.,,..,,........ Prediction of dangerous tides / storm surges (see Figure 3)’ Likely area of flood rain’ Details of severe cyclone Thomas Central pressure’. ...,..,...,............. Location of centre Recent movement’ Extent of destructive winds (ie distance out from centre)’. Maximum wind gusts:................................... Residents between ,,..,.,,.,...,...,.,.,.......,,.. and ,.,,.,,.,.,,,,,,,.,,.,,.,,,,,,,., are advised to take precautions and listen for further advices. The next advice will be issued at y December 30, 1993 Tropical Cyclone Rewa: December 30, 1993 - January 22, 1994 December 31, 1993 January 1, 1994 The Weather Bureau reports that it is keeping a close watch on tropical cyclone Rewa, about 1,200km of the Queensland coast. The category two cyclone is south-west of the Solomon Islands and moving west-southwest at about 30km/h. January 2-12, 1994 A warning is issued to shipping, with cyclone Rewa centred about 800km north-east of Cairns, Rewa is producing wind gusts between 125 and 170km/h. January 13, 1994 Rewa, is upgraded to a category three tropical cyclone- now rated as ‘severe’. The cyclone has intensified in the last 24 hours January 17, 1994 Cyclone Rewa moves parallel to the Queensland coast, but eventually declines in intensity and wind speed, and appears to ~breakdown’ near New Caledonia January 18, 1994 Cyclone Rewa appears to ‘re-form’ off the Far North Queensland coast. It is given its old name back by the Papua New Guinea cyclone centre It has a central pressure of 985 hectopascals. January 19, 1994 Cyclone Rewa lying 680km north-east of Gladstone and moving closer to the Queensland coast. Fears of a major storm surge associated with cyclone Rewa ease as the cyclone’s movement slows It is now 280 km east of Mackay. January 20, 1994 Ports are closed, ships are told to head to sea to weather the storm, flights to resort islands are cancelled and a major army exercise is called off as Rewa - now a catec’ory three cyclone - gets closer to the coast. A cyclone warning is current for the coast betweer ackay and Gladstone. January 21, 1994 The cyclone weakens slightly to a category two as it moves closer to the coast, but still batters the shore with heavy seas, gale-force winds and torrential rain. A child dies in flash-floods in Bnsbane and a fishing trawler with two crew members is stranded at sea until a rescue is successfully completed using an army helicopter January 22, 1994 Three people die in car crashes directly linked to Rewa’s treacherous inditions. Three men are washed overboard from a small boat and are found clinging to a beacon 15 hours later. Flash-flooding submerges cars and damages about 100 houses. The cyclone changes direction and heads out to sea. The Bureau of Meteorology says that cyclone Rewa is no longer a threat. It is now 300 km east of Fraser Island, off south-east Queensland and has been downgraded to a category one. Section 5 - 7~ppical Cyclones 59 Rewa: Diary of a Tropical Cyclone Figure 1 Activities I Using information in Figure 1 , answer the following: a Why could Rewa be considered as two tropical cyclones rather than one? b Cyclone Rewa changed its behaviour in a number of ways betweenDecember 30, 1993 and January 22, :1994. Outline at least three characteristics of the cyclone that changed in this time? c Why do you think the Bureau of Meteorology uses cyclone severity categories (eg category one, two, three etc)? d Cyclone Rewa never crossed the Queensland coast, and yet it still caused significant damage. Why was this the case? e Why do you think ships were advised to weather the storm by heading out to sea, rather than sheltering in a port? I In one incident, coal shipments at the port of Hay Point were disrupted by the cyclone. Suggest at least three other economic costs which may have resulted fromthe activities of cyclone Rewa along the Queensland coast. g Cyclone Rewa eventually died out as it headed south-east away from Queensland. Explain why. 23 DE Figure 1: Cyr~Ionc Tracy, I)ccernber 1974 - Di :•y of a dic~Fe-r adapted from 1/a~.ards Duassers wtd SunJ., ithacr& L)ntjsrers Orpitii~tuiort. 1992 V ND; ~‘~-•~ F-OURCFIOY / L~. ft flgure 3~ Aerial v1~w ol fl4irw an’s iicwthem suburh. Cht~sini~ rnorruog 1074 C4iJ’!Jd tio Case Study: Cyclone Tracy, Darwin, 1974 Tropica/ Cyclone.c Cyclone Tracy, December 1974 - Diary of a disaster December 20: December 21: A ~ow prcssurc system i~lentificd in the AnEw-a Sc-a. SatdIi~e photographs show the low moving sk,wly south-westwards, 930pm - A cyclone warning ]S ~ssucd arid the nne ~Tracy is givco. December 22: 3 3Opm - Radar m Darw iii clearly identifies the eye aiboui 2% htninetres dcvelopmcrit and iritensiricauon of the cyclone is endent. north oF the C~(y, Rapid Uecemhcr 23; Drcrmber 24: December 25~ 7 3O~m - Eve dsacneter has shrunk to 12km (a suong indicator of intensificationi The centre is jusi oil the northern tip of McMI In island (see Figure 2~ aix] is st~II iii ~vi ri~ Nauth-wesL, 91X)am ~o 3 OOprrt - Strung winds and heavy rain ~re reported from Barhu~t arid Melville islands, Midnight - Tracy changes dir c&il and heads south. Winds strengthen at the automatic weather station at Cape Eotircroy. 6-00 içi fl)Oaut - Average wind speeds reach ~20kmTh at Cape loureroy as Tracy rounds the so.ith-west conier ol Dathurst Island Noorr Tracy again changes cOurse arid heads south-west towards Darwiit 1230pm - Cyclone warnic~g issuod to Danwin residcnla advising that Tracy should cross the coast cely on Christmas Day Mid n’gth to 1 am - Whirl gusts stronger than IOOIIIIJII commence in Daxwiri I MO to 3 (JOn - Numerous reports of severe damage in and around Darwin. Both radio Mait ns lail 3.DC}arn - Maximum rccordcd wind gusto 217km/h i-ccurded before anernomeler recording system faik Torrenthi rain falling - Cyclone’s eye directly cwethead arid caIrn i~ felt for aLxiui 30 rnnite~ 430am~ Extreme winds resume hut this Lame from the opposite direction. 6 OQarn - Traeys centre lo~atc.d near Howard Springs with winds abating ira Dat-win Midday - Alter cro~sn~ Adelaide River, Tracy quickly degenetates FntO a tarn deprvss ion. I. -i 24 DEC _______ BEAGLE GULF{:icD 25 DEC ~L~KR!~NRADAR oD4OS~LJ ~-D kiIe~rneLr~ / y’<%. Figure 2: Tack of Cyck]rn~ Tracy showing apv1~}stmitc honily posttaons of the cyt Death and Damage, Cyclone Tracy Tracy claimed 49 Lives in Dniri • A FurLher 16 lives were ]osr ci sea on several smj[l vessels winch were in the path of the cyclone. 6S0 people were rrcaird [or injtancs. • 35,000 people (our of a population of 43,000) were evacuated From Darwin in the days lollowang the cyclune 23~00O ol these Were by air in (lie lafl!est airlift operation evei attempted in Australia. Relid teams. coordiriasted by the N~uirM Disasters Organtisation. cleaned up wreck~e and debris, dis infected huLl di ngs and colkctcd and recorded pcrsottal possessions~ • About 913 per cent of flarwin~ 12.000 homes woat damaged IX destroyed. • Msured property tosses exceeded 5700 iriil]iün and total estimated costs were more ihan Si .5 billion. Qdopledfrom ilutardr. Disas:m a’ad Suniva)’. Ois-a.ci~rz Org niswMsi, 1992. ~~opicae Cyclones 61 Case Study: Cyc/one Tracy, Danvin, 1974 (coutd) Activities 1 Study the information in Figures 1 and 2 arid ~p~wer the following; a Why did Danvin seem safe from the [WI impact of cyclone Tracy until noon or. December 23? h How might the following have influenced peoPle’s preparations for the arrival ci the cyclone; ‘ ihe date on which it occurred; • the time of day at which it arrived; • the fact thai other cyclones had appeared to be heading towards Darwin ar. the past. but had changed direction to miss the city? c Why do you think the failure o~ both radio stations at the beginning of the most intense cyclone activity was seen as a rnsjor setback? d Many people in Darwin thought the cyclone was over when thrt eye arrived. What problems - ‘ Figure4 __________ might have resulted from this? e Bplatn why the winds picked up horn ‘he opposite direction alter the rwe had passed. How might this have cattsed additional problems? F Locate Adelaide River on ~ map in yotr atlas. Why do you think Tracy had degenerated into ~ rain depres~iort by the time it reached here. 2 Look at the info rmatiort in Figure 4- a Why do yoc~ think more than three-quarters of Darwin~i re-sidents were evacuated after the cyclone? Suggest some of the problems which may have been involved in such a large scale evacuation. Figun Sircet srntc. D-.irwin. Christmas n~orrpirt~ 1974. b Why do you think all btzildirigs were dis}nlected alter the cyclone? 3 Study Figure 1 Why do you think corrugated iron can be particularly dangerous during a tropical cyclone? Figisr-e 6: D@niage to clcvaied heit~e tollowing ~ydone Ti~y. 4 Study Figure 6. Why do ~c’u think most of the L)~irwan. l W?-1 damage caused by Cyclone Tracy was tO elevated rather than Slow-set’ houses? Storm Surges: What are they? How do they happen? A storm surge is a raised dome of sea water typically 60km to 80km across and 2 metres to 5 metres above normal sea level. As a tropical cyclone reaches the coast, the huge winds whip up the sea and push the dome of water over low-lying coastal areas. The waves aod sea water can move inland quite quickly, damaging buildings and cutting off escape routes. There is a high risk of drowning. A storm surge is NOT the same as a tsunami - a huge wave caused by an earthquake which comes crashing into shore. A storm surge comes in like a rapidly rising tide, except it may be extremely dangerous and destructive. Every tropical cyclone produces a storm surge but not all storm surges are dangerous. The height of the storm surge depends on: • The intensity of the cyclone - the stronger the winds the higher the surge. • The speed of the cyclone - the faster the cyclone crosses the coast the higher the surge. • The angle at which the cyclone crosses the coast crossing at right angles will increase the height. • The shape of the seafloor - the more gentle the slope the greater the surge. • Local features such as bays, headlands and islands - can funnel the surge and amplify its height. The extent of flooding will depend on the tide at the time the cyclone and storm surge reach the coast. If this occurs at high tide, the floodin2 will be at its worst. S ~iGH rice LEVEL _3mstirge~~ — CYCLONE STORM SURGE Figure 2: Storm surge formation 62 Section 5 Storm Surges Tropical_C~yctones Figure 1 Activities Fill in the blanks in the following sentences using information in Figures 1 and 2. Check your answers by finding them in the puzzle on the right. 1 Every cyclone produces a storm surge. 2 During a storm surge, — — — water flows over — — — - lying land, where it may cause damage to 3 Three examples of local features which may amplify the height of a storm surge are — — and 4 The and ofatropical cyclone will influence the height of a storm surge. 5 is acommoncause of deathdurirsg a storm surge.. 6 A storm surge raises the level of sea water two to five metres above level. 7 The at which a cyclone crosses the coast ~J~JP 1JJCfl4 LIDCi’O~AS~T[SMSPE~ I ~A~L7EJ11PEI BLEATLSD D IIWTE WA S!LO~ L~E A~O D~O~EJ~ A B DLN~VJ:~J~¶~ThN LlffWlI~NEWAI~N!DTf~i]~s~L H~f ElA~ G~AlIIS L A N~DIS N Si SIHE~A D L A[N~D~ S and the of the sea floor will both influence the size of a storm surge. 8 A storm surge is a raised — — — — of sea water which is like a rapidly rising — — — — 9 A storm surge is not the same as a tidal — — — — 10 The huge associated with a tropical cyclone, push sea water over low-lying areas. 11 The more gentle the of the sea floor, the greater the storm surge. HAZARD DATA + Emergency rnari~igernetit can be defined as a process winch is used irk pritenilally ltnsrdotis situations to minimise unccrtaancics and ma~inse public safety. • ‘This process may cover everythIng trorn a minor. localisad incident tD ii ma~or disaster. • Emergency managemcnt is piat into op:rLI(iOfl bcfere or dunrig a hnardoin nlwwcrn to: - mimmise community vulnerability to bazsrds - m~ximisc pcople’s ‘~afcty - rrnmrnise damage and Loss of property - help with reShilitation arid reccwery. a a Figure 2: Ernetrncy rnartagemen~ — ) HA lARD ANALYSIS L PREVENTION/N1~IGATION RESPONSE PREPARATION Ti-IF EMERGENCY EVENT RECOVERY Sectiwi 5 m~p~& Cvclotirs 63 Emergency Management: Tropica/ Cyclones Activities 1 Using a major flood as an example of an emergencyr write e~eh of the Ioflcawiag actions in the appropriate place in the right-hand column of Figure 2: • relocahon of vaJuabks and equipment • cortstructiort ot cyclone shWters • studying cyclone history and behaviour • stockpiling of sandbitgs to protect again-st coastal flooding • drawing up of maps showing high nsk aTea± ____________________________ • cyclone-proofing ot buildings • providing medicine arid Food for victims • investigating how the cyclone behaved arid comparing it to past events • restonng utilities and cornrriumty services • search, rescue and evacuation operations • issuing warnings during the cydone • rehearsal of counter-disaster plans • installing instruments to monitor wind 5p’eecl buildmg of storm surge barriers On the coast preparation of emergcncy/FNaCUatiOn lcd nMSlIatior~ of war~nng system • repatring cyclone-d3maged bucidings • supporting cyclone Victims. 2 U~cirtg Ftgure 2 to help you, say which sbge o1 emergency management iS shown in Figure 1. Stages in enu~rgency managtrneni What ft invctv€s E~~ampJn oFactioi-ts tde-ncirying the bazaiti • Pr~vkliri~ W~rnir~g o~ ~ d~veLup~rtg thItII • Working twit comrturnity vMliiersbphIv • Prc’~crirIrig th~ thrraL c’~ert!i*tIl1~ Mirnwi sing the impet csftIi~ event • Altrttcig peottie icr the threat • Raismg awareness of prqtontian ~n4~ • AflocBtLng rc-~ponsibihuirs S!uckjitlrng es.scrth~i fooc a~td eqktipFA~nt A major flood RESPONSE COmh~LtUIg ihc CaI~5C ~nrJ eI-fcct of Lhc hnard - Assisung people atfccted • Miriartusrn~ cue-ct @1 repeacS CVCDES Clesoiq up arid repu~ring damage • On-going medical ~nahncrtt Cowiseltuig oIncthns • Firt~zq&I, legal awl wii~- nippon • Revision Ihn*rJ analysis • Evahkslion ti! pnweniirr and miligatiori CYCLONE ACTION! BEFORE THE CYCLONE SEASON • Have a portable radio and torch with fresh, spare batteries. • Check your house is in good condition, particularly the roof. • Trim tree branches clear of your house. Clear property of loose items likely to cause damage in high winds Know your community disaster plan. In case of storm tide warning, identify your nearest safe high area Create an emergency kit of tinned food, water containers, emergency lighting, first aid kit, medicines, tape and plastic bags. UPON A CYCLONE WARNING • Listen to your radio and TV for further information. • Board or tape windows, store loose articles inside. • Lock up pets, fill water containers, fuel car and place under cover. Check your emergency kit and put spare clothing and shoes in plastic bags. ON WARNING OF A LOCAL EVACUATION Switch off electricity, gas, etc and lock your house upon leaving Don’t forget your emergency kit. Follow instructions from emergency personnel WHEN THE CYCLONE STRIKES Stay inside and shelter in the strongest pan of the house (eg bathroom or cellar). • Protect yourself with mattress, blankets Anchor yourself to a strong fixture (such as water pipes) or get under a strong table. • Beware the calm eye. Remain indoors until advised the cyclone has passed. AFTER THE CYCLONE • Don’t go outside until advised officially or you are positive the cyclone has passed Listen to your radio for further information and advice. • If you had to evacuate, don’t go home until advised Use route recommended. Above all: Don’t ignore warnings! 64 Section 5 Cyclone Survival and Property Protection Truprci±l Cyclones Activities Figure I: Cyclone Action! adapted from Emergency Mann gemeiu A as tra/ia, canberra Study Figure 1 above and answer the following: a Explain why you would take the following actions upon hearing a cyclone warning: • tape up windows • fill your car up with fuel • fill water containers b What problems might arise if you were to rely only on radio and television for cyclone information? c What does ‘beware the calm eye’ mean? 2 Construct a poster, suitable for display in a cyclone-prone area, on one of the sections of Figure 1 Your poster should (i) be designed to capture the viewers attention by usmg illustrations, and (ii) contain accurate supporting written information The Scenario An intense tropical cyclone has passed through the middle of your city at 6.OOam on January 26. The Bureau of Meteorology issued warnings of serious damage for three days prior to the cyclone’s arrival and accurately predicted the path of the cyclone over the 12 hours before it crossed the coast. During this time warnings were broadcast to residents of your city each hour. Torrential rain fell for 24 hours prior to the cyclone’s arrival and for about 4 more hours after it had passed. Maximum wind gusts of more than 200km/h were reported, with the passage of the eye lasting about 20 minutes. A storm surge of about 3 metres flooded many low-lying areas along the coast, and several people have been reported as missing in the heavy seas. It is now midday - six hours after the cyclone has passed. The scene is one of major devastation. About half of the houses in your city have been demolished by the winds, while almost all of the shacks along the beachfront have been swept away by the storm surge. Twenty people are already confirmed dead, with a further 200 still missing. Emergency service personnel have begun arriving from the south, but communications have been hampered by the loss of broadcast radio and television at the height of the storm. The Characters The Kelly family - The four of us live in a weatherboard house on the beach. The house is on stilts, with a corrugated iron roof and a large windows at the front. We have just moved in, and haven’t really had time to think about preparing for the cyclone season. Nursing staff at the local hospital - We’ve done some specialist training, along with the ambulance team, on the types of injuries to expect after a tropical cyclone. However, I doubt that the hospital could cope if a major cyclone hit. Local shopkeeper - All of the shops in our centre have been built to withstand major cyclone damage. We are also well stocked to feed and cloth victims of the cyclone - provided looters don’t get to our shops first! The Marston family - We’re about 25 km inland from town on a large property. I’m not quite sure how the cyclone will affect my family, our home and our 1000 head of cattle. Social workers - We can provide post-trauma stress counselling for cyclone victims. This is an essential part of the recovery process. Emergency service personnel - We’ve worked hard to prepare for a major disaster. There are many jobs we can do in supporting victims, cleaning up and rebuilding. However, if evacuation is required we’re going to need outside help. The local council - Out town hail is likely to be a focal point in the event of a major catastrophe. We’ve made sure that this and other public buildings can resist damage and remain safe for people after a cyclone. Our building inspector has also enforced stricter cyclone- proof features in all new homes over the last two years. The Capuano family - Our place is in the middle of town and is about a year old. It was built after the new rules came in on cyclone-proofing of houses. We’ve also tried to take a range of other precautions prior to the cyclone season Figure 1 Section 5 Tropical Cvclciner 65 Community Responses to a Tropical Cyclone Activities Study Figures 1 and 2. 1 Divide into groups representing the various people shown in Figure 2. 2 In your groups, discuss how you prepared for the cyclone, the impact it had on you and how you responded after the cyclone. 3 Staying in your groups, prepare for a meeting of the community to discuss your experiences before, during and after the cyclone. The aim of the meeting is to come up with a range of actions which could improve the community’s response to future cyclones. 4 The group representing the council should prepare an agenda for the meeting, which allows all groups a chance to have their say. They should also appoint a ‘mayor’ to chair the meeting. 5 Each class member comes to the meeting at the Figure 2 town hail wearing their name tags for identification (This may involve allocating different roles to people within each group) 6 The meeting is conducted and a list of recommendations is drawn up for display and public comment. Crossword: tropical cyclones Down Section 5 Tropical Cyclones 66 Across 6 Tropical cyclones are called in Asia. 8 Instrument used for measuring wind speed. 9 Tropical cyclones are areas of intense pressure. 10 Another name for a high pressure system. 13 Huge ocean waves whipped up by tropical cyclones. 17 Australian state where tropical cyclones are common 18 Tropical cyclones over the Bay of drive storm surges onto the coast of Bangladesh. 21 State of the USA where hurricanes are common. 22 This natural hazard may often result from a tropical cyclone. 23 Sheets of roofing can be lethal during a tropical cyclone 24 Port in Western Australia narrowly avoided damage from cyclone Orson in 1989. 25 Pacific Island country which experiences regular and disastrous tropical cyclones 26 Tropical cyclones only occur in the I A very strong wind. 2 City hit by cyclone Tracy in 1974. 3 Lines on a weather map joining places of equal air pressure. 4 The Scale uses everyday observations to measure and describe wind conditions. 5 Units used to measure wind speed. 7 A tropical cyclone in the USA is called a 11 Large, anvil-shaped clouds associated with the formation of tropical cyclones. 12 An area of calm conditions at the centre of a tropical cyclone. 14 Cyclone was the most damaging in Australia’s history. 15 System used for tracking tropical cyclones. 16 The Bureau of issues cyclone warnings. 19 Powerful, funnel-shaped storms which form over land (not to be confused with tropical cyclones). 20 Using photographs, meteorologists are able to tell the location and size of tropical cyclones. In this section 68 69 70 72 75 76 78 so 82 “7 Section 6 The Drought Hazard Page • Drought: Glossary of Key Terms • Defining Drought • The Drought Experience • El Xiñci and Drought Prediction • Drought and its Related Effects • The ‘Drought Watch’ System • Statistic:tl.W Speaktng: The ‘Great Dry’ 1982-83 • Drought i~nd Farm Management • Crosswvrd: Drought Drought: Glossary of Key Terms Drought: A lack of sufficient water to meet essential needs for an unusually long period of time. Drought management: A range of techniques and strategies which aim to reduce the impact of drought (particularly applicable to farming areas). El Niño: A term originally used to describe the appearance of a warm ocean current off the South American coast, adjacent to Peru and Ecuador, around Christmas. El Niflo is now used more broadly to describe a sequence of changes in the circulation of water and air across the Pacific Ocean, which result in major alterations to weather patterns. Famine: An extreme scarcity of food often associated with extended drought conditions. Southern Oscillation: The year to year variation in the strength of the Walker Circulation. Southern Oscillation Index: An indicator of the strength of the Walker Circulation, calculated using the difference in air pressure between Tahiti and Darwin. Walker Circulation: The pattern of air circulation across the equatorial Pacific. In a normal Walker Circulation easterly trade winds bring warm surface water and warm moist air into the western Pacific Ocean. This air rises to high levels in the atmosphere and travels eastwards before sinking over the eastern Pacific. Wide variations in the strength and patterns of the Walker circulation occur from year to year. 68 Activities 1 The Difficulties in Defining Drought Drought has always been difficult to define, since it means different things to d(fferent people. There are meteorological droughts, feed droughts and water droughts, and the one event can effect d(fferent land uses and managers d~erently. The practical problems of defining drought are that. • we don ~ know when it starts, and • we don’t know how long it is going to last In effect, drought is one of the risks involved in carrying out a commercial business in a variable and largely unpredictable climate. No two droughts are the same and responses to them need to differ because the nature, extent and degree of the risks are changing constantly from Managing for Drought’, P 3. Walker, Department of Conservation and Land Management, 1992 There have been several definitions of drought, none of which has been completely satisfactory. The simple description ‘dryness due to a lack of rain ‘for example, could be applied to many inland areas where such conditions would be regarded as normal rather than a drought situation The most satisfactory definition depends on the acceptance of drought as a supply and demand phenomenon. Thus drought occurs when there is ‘lack of sufficient water to meet normal requirements’. However, nhat is drought to one section of the community (e.g. a market gardener) may not be regarded as drought by another (e.g. a sheep farmer). from ‘Drought in Australia’, the Bureau of Meteorology Drought is not only the result of a lack of rainfalL It occurs when there is a reduction in the overall availability of water.The presence or absence of drought ‘na’ therefore depend on the storage, use and management of water supplies as much as on the amount of rain that falls. from ‘Hazard Geography’, C. Dolan, Longman Cheshire, Melbourne, 1994. Figure 1 Figure 2: Factors determining watcr availability SectiQli 6 DrouRhi 69 Defining Drought Using the information in Figure 1 a Make a list of reasons why it is difficult to define ‘drought’. b Explain the likely meanings of each of the following: meteorological droughts,feed droughts, water droughts. c What problems would be created for the following people in not knowing when a drought had started and how long it was going to last • a sheep farmer in semi-arid Australia; ‘ a fruit grower on the Murray River; • the authority managing the water supply of a city. d Why is the description of drought as ‘dryness due to a lack of rain’ not completely accurate? e What does it mean to say that drought is ‘a supply arid demand phenomenon” f Explain why each of the following would have very different views of what is meant by ‘sufficient water’. • a desert nomad in southern Africa; • a wheat farmer in central New South Wales, • a market gardener near Melbourne. 2 Read the last quotation in Figure 1, and then complete Figure 2 by correctly adding each of the following in the spaces provided’ rIvers, snow, crops, industry, underground basins, domes tic,farm dams, tanks, native flora and fauna, sleet, salinisation, pastures, rivers flowing into the sea, reservoirs, public utilities, evaporation. I ~ ‘~‘ 0 Just about all the sheep have been sold off or died. It’s nothing for flocks of 7000 or 8000 to be reduced to just a couple of hundred. Where we used to go to a shed to pick up a semi full of wool, we can get it in the back of a ute. One bloke at Bollon last year produced /27 bales. This year! sent out an Fl00 and picked up six. The bank manager had taken his cheque book. He went away to work in Moree, leaving his sheep tofendfor themselves. Most of them were dead under the trees and in the bore drains, Mick McGrath, a wool buyer from the western Queensland town of St George, describing the drought conditions of 1993. In Courier Mail, April 15, 1993 Saltbush roots die off releasing the plant to tumble as roly-polies over and over until they pile high against the fences. The paddocks become so hard the machines will not penetrate, or so loose and dusty that they dare not for fear of losing their topsoil. This affects the next season’s crop and income. Hardships are so extreme from lack of food and water, and heat, that aged animals die. Their bones shine white as they lie bleached by the blazing sun. Only the young and virile are able to survive. Win Clipsam, describing the 1939-45 drought years in western New South Wales From the air, huge dry areas resemble a war zone, where drought has defoliated the trees as thoroughly as Agent Orange, and great swathes of gouged earth lie covered in flattened mu/ga trees stripped bare by hungry stock The driest landscape is transformed into a bone-scattered open graveyard as staggering sheep and starving kangaroos collapse and die in the open or are trapped in mud at the bottom of empty dams, their bodies picked clean in a matter of hours by crows, eagles and feral pigs. An account of drought conditions in Queensland in 1993. From ‘A Cry from the Dying Heart’, Janet Hawley, in Good Weekend, September 4, 1993 Section 6 Drought 70 The Drought Experience Read the following personal observations and experieces of drought. (1) At the end of the second dry August, the people sat in the shade of the empty granaries or under the doorways and walls of the compound, almost everything around them turned to the same parched colour so that only the harsh light and dusty shade defined the familiar shapes of the village. The women still walked to buy cans of water when they could and the men came and went looking for work But the elders scarcely moved from morning to night and no children played. ‘Yel Ka-ye’the people said when you asked honestly how they were - ‘no problems’. ‘Laa,fi-Bala’, mumured the elders - ‘I have peace and health’. And they were all starving. Every live leaf had been collected and even in the towns there was no food. Finally, when even the red millet had gone and the roots were being boiled, the time came when the infants began to be given back (to die)’ from ‘The Rains. A report from a village in Upper Volta’, New Internationalist, February 1983 (3) (4) (2) Greatcracksopen up inthe soil and writhe across the paddocks. Willy-willys flit in cyclone fashion at random. Their fun is spoilt There’s nota blade of grass or a twig left to swirl and toss. canal FL~ur2 I W~r .‘ir~Jkrt oolftchng w~Lrr, ciaLem Sudsrt Plants dit and d,y up ]cavFT~g the snt surfact exposcd, Wind picks up top~nc[ and currEe~ it sway iii dujtstnrms SCCTIOI1 6 -~~_______ -_____ ________ - The Drought Experience (cc’ntd) Activities I Unng info rma Lion from the four accoui’ts of drought on the previous page, answer the following a Comment on the marn difference between account (1) - frotn Upper Voila in Attica - and the other thzee accounts c’f drought in Australia. b What is meant by ‘wik~willys’ mentioned in account (2)~ What u-n par.t might they have ott a drought-affected kmdsc4pe? c Win CUpsarrt describes some paddocks as ~so hard the machines will not pimetrate# ~J others as #so loose and dusty they dare not (plough them) for fear of tesing their topsoiV. Explain how these Iwo different soil con&trnrni can oenr during periods of drought- Why is loss of topsod a thai-or copeern for farmers? d Account (4) des cnbes mu]g~i trees flattened by farrners Why do you thrnk farmers would uproot mulga in &nes of drought? Mulga trees take 10 years to regenerate. WFufl 1ong-terc~i effects might result from uprooting large areas of these trees? I Study Figure 1. a What evidence from the photograph suggests that this rc.gion of Africa is experiencing drought? r~urr 2: Expcrienccs oIlroiighL h What dangers and danger~ are associated with cc riecting and disinbuting water ]fl this way~ 3 Ustng the accounts on the previous page. as we!] as your own expenenee of drought, complete Figure Thy adding a range of ways in which peapk might expcrience the effects of droughL To help you, two boxes have already been filled in. Add other boxes if you need them S~$3tp bCCOItI€ weak and undemainshed a~ feed declines. Wool yidds are reduced FEnd valuable sicick die or ha’ie to be shot [Experiences of Drought I Section 6 ni-nfl oil? 72 El Niño and Drought Prediction Understanding El Niño - the key ideas The origin of El Niño: El Nub translates from Spanish as ‘the boy child’. The term has traditionally been used by Peruvians who fish for anchovy. It describes the appearance of a warm ocean durrent off the South American coast, adjacent to Peru and Ecuador, around Christmas - hence the reference to the Christ child. This current temporarily displaces nutrient rich cold water, reducing the food source of the anchovy and when the warming is exceptionally strong, completely mining the anchovy harvest. El Niflo - the bigger picture: Research has shown that the El Nub current is only part of large scale Interactions between the ocean and the atmosphere. As a result, the name El Nino is now used more broadly to describe a sequence of changes in the circulation of water across the Pacific Ocean and the islands of Indonesia. These changes in oceanic circulation are accompanied by changes in circulation of the air, resultmg in altered weather patterns across the globe. The Walker circulation: During a normal weather pattern (Figure 3a), easterly trade winds bring warm surface water and warm moist air into the western Pacific Ocean. ‘flus air rises to high levels in the atmosphere and travels eastwards before sinking over the eastern Pacific. This is called a normal Walker circulation (after Ste Gilbert Walker who first described the pattern it in I 920s). In this pattern, the rising air is associated with regions of low pressure and brings soaking rains to northern and eastern Australia. The sinking air is associated with high pressure and dry conditions. The Southern Oscillation: The strength of the Walker Circulation can vary from year to year. This fluctuation is known as the Southern Oscillation When the Walker Circulation pattern is strong, Indonesia and northern and eastern Australia will probably be wetter than normal. During El Niflo episodes (Figure 3b), the Walker Circulation weakens. This is the result of a region of low pressure developing in the central Pacific, so that easterly trade winds are replaced with westerly winds. Warm water and associated moist air, is pushed by these winds towards South America. The amount of moisture reaching Australia/Asia is therefore reduced, leading to drier conditions and possibly drought The Southern Oscillation Index (SOI’: The SOl indicates the strength of the Walker Circulation by measuring the difference in air pressure between Tahiti and Darwin. A positive index indicates that the Walker Circulation is well developed. When an El Nino episode occurs, the SOt will be negative Figure 1 Activities I Read the information in Figure 1, and then place the following terms in the sentences which follow. El Nina, SO!. Walker Circulation. Southern Oscillation (Note: each term may be used more than once) a is an abbreviation for the Southern Oscillation Index b If the is normal, Australia is less likely to experience drought. c If the is negative Australia is more likely to experience drought. d takes its name from a warm ocean current which appears periodically off the coast of South America. e The refers to ‘see-saw’ variations in the Walker Circulation. f Easterly trade winds are associated with a strong pattern. g has had a devastating impact on the anchovy harvest off the Peruvian coast 2 Using information in Figures I and 2 answer the following: a Under a normal Walker Circulation pattern, explain why northern Australia can expect soaking rains. b Explain why each of the following observations would indicate a possible El Niflo episode: • a weakening of the trade wmds and a strengthening of westerly winds over the equatorial Pacific Ocean; con td Section 6 Drought 73 El Niflo and Drought Prediction (contd) Figure 2a: Typical pattern of the Walker Circulation Figure 2b: Walker Circulation during an El Nub year Activities (contd) • A warming of the normally cold waters on the South American coast; • increased cloud cover over the central equatorial Pacific. 3 Place each of the following on the flowchart alongside to show the steps in an El Nino episode: • The amount of moisture reaching Australia is reduced, • A region of low pressure develops in the central Pac~fic. • Drier conditions occur in northern and eastern Atis tralia. • Extended drought may occur. • Warm water and associated moist air, is pushed by roes terly winds towards South America. • Easterly trade winds are replaced roith westerly winds. P L~ I L~ I P P_~_ I 1 r’onut.. El Niño drought disaster feared THE Bureau of Meteorology fears a devastating El Niflo episode could be developing. The bureau deputy regional director, Mr Geoff Crane, yesterday said recent climatic conditions had the potential to plunge eastern Australia into drought late this year. The climatic phenomenon El Nub involves major changes in ocean temperatures and wind and rainfall patterns across the tropical Pacific from Australia to Ecuador. Mr Crane said the most conspicuous indicator of a developing El Niflo was the phase of the Southern Oscillation Index which had been negative since November and in general decline since September, 1988. The index is a calculation based on the difference between atmospheric pressure at Darwin and Tahiti. The index is now -8. It will drastically reduce winter/spring rainfall throughout eastern Australia from the Gulf of Carpentaria to northern Victoria if it declines to about -16 during the next few months. Source: Courier Mail, April 14. 1990 Section 6 74 El Niflo and Drought Prediction (contd) Figure 3 Activities (contd) 4 Read the information in Figure 3. a What is the Southern Oscillation Index? How is it calculated? b What was the basis for the bureau’s prediction that Australia could experience serious drought? c Using the information in Figures 4 and 5, comment on the accuracy of each of the following predictions made in the article: • Australia could be plunged into serious drought late in 1990; • rainfall could be drastically reduced throughout eastern Australia. d Suggest one advantage and one disadvantage of the method of drought prediction described in the article. 5 Using the data in Figure 4, answer the following: a Calculate the total rainfall received for each centre during the period 1 March 1991 to 31 January 1992. Write totals in the spaces at the Charleville, Qid Cairns, QId Wyndham, WA Averagerainfall(mm) Rainfall1/3/91-31/1/92 Averagerainfall(mm) Rainfall1/3/91-31/1/92 Average rainfall (mm) Rainfall1/3/91-31/1/92 March 62.2 0.8 426.1 61.6 140.4 10.4 April 35.1 0.6 200.8 135.2 24.2 35.4 May 36.0 22.6 99.9 99.6 9.5 0.0 June 20.1 0.2 48.3 22.2 2.3 0.0 July 26.6 16.8 28.8 59.8 5.3 0.4 August 21.2 0.0 25.3 4.8 0.0 0.0 September 21.2 0.6 35.8 0.2 6.6 0.0 October 38.0 9.4 36.7 5.2 14.7 3.8 November 38.3 25.4 90.9 52.0 54.8 57.5 December 53.1 30.0 180.4 97.8 108.1 14.8 January 71.4 28.2 410.3 127.6 158.0 107.3 TOTAL 423.2 1583.3 523.9 Figure 4: Rainfall chart for selected centres showing comparison between average rainfall and rainfall during an El Nub episode, 1 March 1991 to 31 January 1992 Figure 5: Area of Australia affected by El Niflo related drought, I March 1991 to 31 January 1992 bottom of the table. b Which of the centres do you think was most seriously affected by the drought? Explain your choice, and say what additional information you would need to make a more accurate assessment. c Cairns received more rainfall in the drought period shown, than Charlevulle receives under average conditions. How can Cairns still be considered drought-affected? d At which point during the drought period do you think the people of Wyndham would have (i) known that the drought had started, (ii) thought that the thought had broken and (iii) realised that the drought was over? Explain your answers in each case. Desertificaiion Less of wps~l Daststorrns Psdueed soil renil~Ly Increased busflfiit risk Wind erosion Dtying otitof vegetauoia Loss of groundcover Feral animal damage w crops Fami nc Drought Lack of svfiicient water to meet nonnal requtrements Reduccd ra~ income Loweriag of the Severe water shortages Stunted crops and pastures restr}cIiol]s Death of livestock Lack of water for dririkiri& Reduced food supply Water-borne diseases Pdhaion of water supplies Loss of lift rigure 2: iJiought Scent1 northc,rn South Australia Droughr 1~ Secüon~ -— I.L — — - Drought and its Related Effects Activities I StSy H~uxe] and then answer the folic~wing; a What is meant by ‘lowering of the watertabic~? Why doe it occur during periods of drought? Who might be affectS by a IoweSg of the watertable? b Which cii the effects of drought shown are unlikely to be assocEted with droughi in Australia? Why is this the case? With which regions of the world do you associate these effects? c Research at least two of thi~ following w~iter—bcirrte diseases; schfsrosomiQsis. inaThitz~ ~mdioma, biThania~ hoekworri, dpS*oeo. clwfrrq Find out the cause and effects of these diseases, and ti-ic tegfons of the world most seriously affected. Why are water-borne diseases more likely to cause illness and death during periods of drought? d Eind out what is mean! by ~descrtification’- i.e~ w how and why ~t occurs; a its impact on people arid the land; • the regiom which are currently affected or likely to be aflecti~d in the futu’e~ e Working a-s a class, brainstonn any additional effects cfdrotightnotahowriinFigure 1-Add these to the diagram. f Devise a series of at least three flowtharts using different parts of Figure 1 to show hew the effects ol drought are related. For example; I Severe rst~~d 1 ~~i;;;uce~~i flgure I~ The rebted effccts uf dmu~hx I lJroughi 1.4 w~iIer ~ crop anti J_~ farm L — J J shortages [fftucesj I2!r 2 Study Hgure 2: a Explain the different steps that may have led to the scene shown? b What problems would tho farmer have had to facet • at the tune of the drought; . after the thought broke. 3 a I-low might drought be related to each of the following natural hazards: buth(fres,floats~ bind sthsidcnee (ththng of the laS), b Choose an examp]e of a natural hazard other than drought (e.g feed, bush lire, tropical cvdc’rte) arid construct a thart similar to 1~igure 1 to show its range of relatw:E etMcts. HAZARD DATA • The Bureau of Meteorology has maintained a regular ‘Drought Watch’ system for Australia since 1965. • The Bureau issues monthly ‘Drought Statements’ once an unusually dry period begins to develop over any part of Australia. • The statements are issued until rainfall deficiencies finish. • The statements include a description of the main features of the rainfall pattern (Figure 1) and maps showing the extent of rainfall deficiencies (Figure 2). Activities I coiud Section 6 Drought 76 The ‘Dro tight Watch’ System Statement on Drought Issued by the Bureau of Meteorology on 10 August 1994 Overview Dr John Zillman, the Director of Meteorology, said today that a continuation of dry weather over the southern half of the continent during July, exacerbated rainfall deficiencies which have developed during the past 5 months. Eastern Australia is the most seriously affected region, hut rainfall deficits are also present in South and Western Australia. Heavy rain during the first few days of August eased the very dry conditions in parts of eastern Tasmania but was insufficient to alleviate the rainfall deficiencies in that part of the state. Rainfall deficient areas for the four month period ending July 1994 Following an early end to the wet season over Queensland, rainfall deficiencies have developed in the southeast of that state during the subsequent four months to the end of July. Rainfall has also been well below average over New South Wales and Victoria over the last four months with some areas recording their driest April to July period on record. A broad region with rainfall deficiency extends southward from east~central Queensland to southern Victoria. Parts of the east coast and adjacent inland of Tasmania, parts of southern South Australia and southwest Western Australia are also experiencing rainfall deficits. Rainfall deficient areas for the five month period ending July 1994 Rainfall deficits for the five month period ending July cover similar areas as the four month period in Western Australia and Tasmania. Recent deficiencies in Queensland are confined to the southern inland border districts. In South Australia. deficiencies arc similar but more extensive. Rainfall deficits in Victoria and New South Wales arc again similar to the four month period but extend further westward. The accompanying maps (next page) show the extent of rainfall deficiencies for the four and five month periods to the end of July 1994. Source: Bureau of Meteorology, 1994 Figure 1 Read the information in Figure 1 and then complete the following: a If an area is experiencing ‘rainfall deficiency’ over the periods described does this mean that it must also be experiencing a drought? Explain your answer. b Using information in Figures 2 and 3, describe the areas of Queensland experiencing rainfall deficiencies for the two periods shown. Using information in Figure 1, account for the difference between the two maps. c Describe how each of the following might make use of ‘Drought Statements’: • an agricultural advisor in a wheat growing area; • the water authority in a state experiencing widespread rainfall deficiencies; • a rural business which supplies emergency fodder to farmers; • a newspaper in a rural area; • a government department responsible for determining the need for drought relief. 2 Using information in Figures 2 and 3, insert each of the following into the appropriate spaces in the statements below: central New South Wales, St Helens, Geraldton, South Aust ratio, southern Queensland. • Deficiencies are more extensive in in the five month period ending July 1994. • Severe deficiencies occurred in over both periods shown. • In 1994, a large area in experienced its driest April to July on record. • Serious deficiencies occurred in over both periods shown. • The wet season in appears to have ended in March. AS ~eART • FAa L!~’ H~I~n. Section 6 Drought 77 The ‘Drought Watch’ System (contd) Figure 2: Rainfall deficiencies for the 5 month period I March to3l July, 1994 Figure 3: Rainfall deficiencies for the 4 month period 1 April to 31 July, 1994 Activities la HAZARD DATA • For an 11 month period from March 1982 to February 1983 Large parts of eastern Australia suffered their lowest rainfall on record. • The impact of the Great Dry’ was felt most in farming areas. For example: - 86 million sheep and 14 million cattle were deprived of food and water (many had to be destroyed); wheat production fell by 37 per cent, with similar falls in the production of barley, oats, rice, cotton and sugar; unemployment in rural areas rose, reaching 40 per cent in some areas. • Water storages virtually dried up (eg by February 1983 in NSW, the Blowering. Burrinjuck, Hume, Wyangala and Keepit Reservoirs had all been reduced to less than 6 per cent of full capacity) b. Horsham, Victoria - 1982 Monthly rainfall and temperatures (mean maximums) C. 35 30 0 25 ~ 15 J10 0 120 100 so 0 60 a ~ 40 a 20 n Horsham, Victoria Average rainfall and mean maximum temperatures * 35 30 Q25 20 15 0, to H 5 120 tOO so E .~ 40 a 20 •- —. ..--%‘ \~ ~%s sb--.’ A’ ,e~ T J ‘F M A M’J J A S 0 Months Figure 1: a, h & c Source: Bureau of Meteorology ND J F MAM J 3 A SON D Months * Figures calculated over the period 1873-1993 coosd Section 6 flrn,, ,,ht 78 Statistically Speaking: The ‘Great Dry’ 1982-83 Graph the rainfall and temperature statistics in Figure la onto the axes provided in Figure lb. b Describe the major differences between Horsham’s rainfall pattern in 1982 and the average pattern shown in Figure Ic. c Horsharn is in one of Australia’s major wheat growing regions. Why do you think the rainfall pattern in 1982 was particularly damaging for wheat farmers in the area? (Think about the growing season for wheat in southern Australia). 2 a Graph the 1982 rainfall figures for Dubbo in Figure 2a onto the axes provided in Figure 2b. b How does the pattern of rainfall experienced by Dubbo in 1982 differ from the average pattern shown in Figure 2a? a. FIORSHAM. 1982 Mean Max Temperature °C Rainfall mm 3 F M A M 30.8 29.8 27.1 21.4 16.5 13.1 23.6 9.4 22.6 15.6 23.6 22.8 J J A S 0 N D Totall9S2 rainfall 13.3 18.6 18.3 21.3 28.7 28.4 13.8 7.0 15.4 13.4 10.6 3.8 L~ffJ 3 F MAM I Months A S 0 N’tJ I The ‘drought period’ was 1/4/82 to 28/2/83 2 The average rainfall for this period based on past figures 3 Percentage of rain falling during the ‘drought period’ calculated against expected rainfall. Figure 3: Rainfall at selected drought locations, 1982-83 Source: Bureau of Meteorology Figure 4 Q,.rt,nn 6 Drought 79 Statistically Speaking: The ‘Great Dry’ 1982-83 (contd) a. DUBBO.NSW LI F M A M LI I A S 0 N D Totall982 rainfall Ave.MonthlyRainfall(mm)* 32.9 32.4 27.6 25.3 20.9 15.8 16.2 22.4 21.7 26.2 32.8 33,4 ________ l982MonthlyRainfall (mm) 39.7 33.8 118.6 8.2 19.3 19.1 9.5 0.0 14.4 18.3 5.6 83,4 * Figures calculated over the period 1870-1993 Activities (contd) b. Ijubbo, NSW: Monthly Rainfall 1982 c Calculate the total rainfall for Dubbo in 1982, and write it in the box in Figure 2a. Why does 120 this total disguise the severity of the 1982 drought? tot) d By comparing Figures lc and 2b, describe the differences in the rainfall pattern for Horsham and Dubbo. Comment on the effectiveness of .Location Rainf all for drought p eriod 1 Total Expected2 Percentage (rum) (mm) received 3 F3enalla 199 614 32 Horsham 110 423 26 Melbourne 338 596 Bourke 105 305 Condobolin 118 376 Jerilderie 85 350 Adelaide 232 458 Port Augusta 72 194 Charlevilte 150 412 Cloncurry 83 374 Tamworth 268 625 Dubbo 270 540 Dalby 378 611 80 .Eoo .~ 40 a: 20 0’ Figure 2: a&b Source: Bureau of Meteorology rainfall in both centres (i.e. the amount of moisture that is available for plant growth). 3 a Complete Figure 3 by calculating the percentage of rain that fell during the drought period against expected rainfall for each centre. To help you, the figures for Benalla and Horsham have already been calculated. b Do the figures in Figure 3 suggest that the drought was more severe in some areas than in others? Explain your answer. c Dalby received more rain during the ‘drought period’ than several other centres would expect under average rainfall conditions. Explain why Dalby was still considered to have experienced a drought during this period. 4 On the blank map of Australia, Figure 4: • add the names of the states; • mark in the cities and towns listed in Figure 3 (use an atlas to help you); * bracket the ‘Percentage received’ figures in Figure 3 alongside of each town; Describe the extent and severity of the 1982-83 drought as revealed by your completed map. What other information would you need to provide a more accurate description? Figure 1: Some drought management strategies Reduced water supply eg selling of stock Stock losses eg improved pastures Reduced crop and fodder yields eg agistnzent of stock Section 6 flrnv, oht 80 Drought and Farm Management Activities 1 Using the information in Figure 1 above, answer the following: a How might having more than one watering point per paddock help reduce erosion? b What advantage would deep rooted crops, such as lucerne, have during a drought? c Describe how contour banks work to help reduce water loss. How do they also assist in reducing soil erosion and pollution of water supplies? d What is meant by ‘stubble retention’? How would it help reduce wind erosion during a drought? e Suggest at least two advantages of the following farm management strategies during an extended period of drought: • maintaining groundcover in paddocks not being cropped; • keeping stocking rates below the maximum possible for a particular area of the farm. f Complete the chart, Figure 2, by filling in possible drought management strategies under each of the effects of drought shown (use your own ideas as well as those shown in Figure 1). Wind and water erosion eg contour banks Ir Figure 2 The effects of drought and possible drought management strategies contd Farm planning and drought management The maio objective in a drought is survival of soil, grasses, animals and farm businesses. The basis for that survival is planning by the individual. Only individual farmers can foresee the problems of drought and act in time to protect their properties. Plans must take into account a number of factors which vary from one location to another. These include: • the size of the area affected by the drought; • the time of the year; • stock prices and the price of bringing in extra feed; • the state of the land and stability of the soil; • options for agistment. The basis of thought management is a whole farm plan which identifies land uses, shelter belts, watering points, fences and soils which are degraded or susceptible to erosion. This plan can then be used to: • identify those areas which should be destocked first and those which can continue to provide food and shelter for stock during a thought; • set aside areas for drought-resistant pastures, and identify areas where pasture or groundcover need improvement; • identify areas where additional fencing, water and trees are required; • set priorities for pest control and strategies for helping wildlife survive. Section 6 Drought 81 Drought and Farm Management (contdi Activities (contd) 2 Outline one advantage and one disadvantage of adopting each of the following drought management strategies in a sheep farming area: • disposing of stock quickly; • retaining stock numbers and bringing in feed in the hope that the drought will break; • seeking agistment for stock outside of the drought-affected area; • selling the farm and moving out of the area. 3 Study the information in Figure 3 and answer the following: a What do you understand by the term ‘whole-farm plan’? What is the role of such a plan in drought management? b What features would you look for in deciding whether a particular paddock should retain stock or be destocked during a drought? c Using examples of pests to support your answer, explain why pest control be an important consideration during a drought? d Imagine Figure 1 is a wheat/sheep farm in your state. Draw up a drought plan for the farm. In your plan, identify those areas where you would: • retain or remove stock; * grow drought-resistant pastures; • retain and improve groundcover; Figure 3 • construct new fencing; • add additional watering points; • plant additional trees; • set priorities for pest control; 4 Complete the puzzle on the left by using the • create habitats for wildlife survival, following clues. If solved correctly the centre Your plan should also include any additional column forms the name of an important water management strategies you would employ in conservation and erosion reduction measure. the event of a drought. Clues I of farm dams keeps out pests and prevents stock losses. 2 stops rabbits, foxes etcfrom competing for food with stock (2 words). 3 Stubble protects the soil. 4 involves transporting stock out of the drought-affected area. 5 Maintaining - cover reduces erosion. 6 Water may result from soil and manure being washed downslope. 7 In drought, soils can become badly_________ 8 provide shelter for stock and protect the soil from wind erosion. 9 pastures survive best in a drought. 10 is a deep-rooted fodder crop. 11 Over- may cause major soil damage. 12 bywindandwaterarelikelytobe more serious during droughts. rjr 3 4 lilt I~ I 5 III II B I I i: ‘‘it’ ii I I I I 14 112 13 fl I 10 I”l I ! I 19 J 18 E : : : 2 ~j : J 23 24 127 I I I I 25 ~28J Across 1261 I I I I I I Down Section 6 fl,-n,.,d. 82 Crossword: Drought 1 The price of _ _ _ — may increase during a drought. 3 Drought-prone country in Africa. 4 Australia may provide _ _ _ to a less developed country which is experiencing a major drought. 5 Water _________ iscommonduringadrought when supplies are low and demand is high. 7 Sheep and cattle ______ usually fall during a drought. 9 Process where productive farming land is turned into desert. 11 These farm animals are often sold cheaply or destroyed during extended drought periods. 12 The people usually worst affected by drought. 16 ‘The Great — ‘ occurred in Australia in 1982-83. 17 Trachoma and hookworm are common water-b ome 21 Drought-tolerant _~ plants need to be developed for Australia’s semi-arid farming areas. 24 A major water user in urban areas. 26 Drought is a lack of sufficient to meet normal requirements. 27 A hazard which often follows a major drought. 28 This state experienced serious and widespread drought in the early 1990s. I Serious food shortage often associated with drought in less developed countries. 2 Farm — _ often dry up during a drought. 3 Another source of moisture, other than rain. 6 Farm ~ may be severely reduced during a drought. 8 Drought conditions may occur if an area of — pressure is lodged over Australia for a long time. 9 These occur when drought conditions combine with strong winds. 10 Loss of topsoil can lead to a decline in soil 13 One of the most drought-prone countries in the world. 14 The ~ — — Wednesday’ bushfires of 1983 followed a period of prolonged drought. 15 The upper level of underground water. 18 often yield poorly in drought years. 19 The failure of expected ~ is one of the most common causes of drought. 22 This is blown away in a dusts torm. 23 Many of Australia’s native plants are highly to dry conditions. 25 In an — — — — region rainfall is barely sufficient to support vegetation. In this section 84 87 89 91 93 94 96 Section 7 The Earthquake Hazard Page • Earthquakes: Glossary of Key Terms • Plates. Faults and Earthquakes Earthquakes - the Different Impacts • Earthquakes in Australia • Case Study: Newcastle, 1989 • Tsunamis • Earthquake-Resistant Buildings • Crossword: Earthquakes 84 Earthquakes: Glossary of Key Terms Crust: The outer shell of the earth including the continents and the ocean floor. Convection currents: In the study of earthquakes, the currents which result from the transfer of heat caused by movement of magma below the crust. These currents in turn cause the plates of the crust to move. Epicentre: The point on the earth’s surface which is directly above the focus of an earthquake. Fault: A crack or fracture along which layers of rock move either vertically or horizontally. Focus: The point of origin of an earthquake. Intraplate earthquakes: Those earthquakes which occur away from the plate margins. Magma: Molten rock below the earth’s surface. Magnitude (of an earthquake): A measure of the relative size of an earthquake based on amplitudes of seismic waves recorded using a seismograph. Magnitude is related to the amount of energy released by an earthquake. Mantle: The layer of the earth beneath the crust. Normal fault: Where the rock on the side hanging over the fracture appears to have moved downward relative to the other side. Plates: Segments of the earth’s crust which ‘float’ on the heavier, semi-molten rock of the mantle below. The edges or boundaries of the plates of the earth’s crust are called plate margins. Seismic waves: Waves which radiate in all directions from the focus of an earthquake. Seismograph: Instrument used for recording and measuring seismic waves. Strike-slip fault: A fault along which movement is parallel to the direction in which the fault runs. Subduction: The process by which one plate descends under another plate. Thrust fault: Where rock layers on the side hanging over the fracture have moved upwards relative to the other side. Transcurrent fault: A large-scale strike-slip fault where the fault surface is steep. Transform fault: A special type of strike-slip fault, along which displacement suddenly stops or changes form. Tsunami: Huge ocean wave normally caused by an earthquake under the sea. HAZARD DATA • Earthquakes result from rocks breaking under stress. • These stresses build up beneath the earth’s surface as a result of the constant movement of the jigsaw-like pieces that make up the thin outer shell of the earth. • These pieces are the plates of the earth’s crust (see Figure 1). There are more than a dozen separate plates of up to 100 km thick making up the crust. • The plates rest on the mantle - the layer of the earth beneath the crust. In its outer layers the mantle is composed partly of molten rock or magma. The continual movement of this molten rock sets up convection currents which cause the plates above to drift slowly in different directions. • The zones of contact between two plates can be a mid- ocean ndge (divergent), subduction zone (convergent), strike-slip fault (sliding) or collision zone (mountain building). See Figure 2. • Movement at these edges (or margins) of plates in this fault zone usually occurs slowly over millions of years. Occasionally, however, enormous stresses buñd up which are released suddenly by fracturing of rocks as the earth’s crust ‘snaps’ into a new position. • This snapping causes the sudden and at times dis astrous vibrations - known as shock waves or seismic waves - we call earthquakes. • The point at which the fracturing occurs, which may be kilometres below the earth’s surface, is called the focus. The point on the surface above the focus is the earthquake’s epicentre. Seismic waves are sent out in all directions from the epicentre. Figure 1: The plates of the earth’s crust. cwitcl, Section 7 Pnnhn,,nI-ar 85 Plates, Faults and Earthquakes Activities 1 Using the information in ‘Hazard Data’ and in Figure 1, answer the following: a Explain why the plates of the earth’s crust move. b One of the largest earthquakes this century occurred in Chile, South America, in 1960. Which plates would have been involved in this earthquake? Describe the directions in which they are moving. c Explain why earthquakes occur where pressure builds up over long periods of time? Why is this pressure more likely to build up where plates are colliding? d Explain why damage from major earthquakes often occurs hundreds of kilometres from the epicentre. e The epicentre for the disastrous Mexico City earthquake of 1985 was 400 kilometres south-west of the city in the Pacific Ocean. Which plates were mvolved in the earthquake? Describe the directions in which plate movement occurred. Plates, Faults and Earthquakes (contd) NORMAL FAULT (common — m~ccee — and on continents) z ‘U a ‘U a. 0 a ThRUST FAULT (common m aubduction ronn and on continents) STRIKE-SUP I- TRANSCURRENT FAULT (such as Sen )ndrsss Fault) orTRAN5FCRM FAULT (common across mid-ocean t ridges wbloh they displace) FIgure 2: The three main types of faulting MARGINS STRESS FOCUS MAGMA Section 7 86 Mid-ocean ridges mark the boundary between two plates which are pulling away from each other. Here the earth forms new crust and volcanoes are common. At the plate boundaries normal faulting occurs producing shallow earthquakes, less than 20km below the surface. Where two plates are converging or colliding with each other one will be thrust over the other (i.e. thrust faulting). Violent earthquakes may result which can occur to depths of 700km. If two continental plates are involved, mountain chains may be built (e.g. the Himalayas). In thrust faulting involving heavier oceanic plates, one plate is pushed or subducted below the other. This may result in the formation of deep ocean trenches (e.g. the Marianas Trench). If a continental and oceanic plate collide, the latter will be subducted, with mountains forming at the edge of the continental plate (e.g. the Andes). Where two plates slide laterally past each other, this is called a transform fault. The San Andreas fault in California is a famous example of a transform fault. Earthquakes associated with transform faults are usually quite shallow, occurring at depths of less than 20 kilometres. Activities (contd) 2 Study the information in Figure 2 and complete the following: a Explain the formation of the Mid-Atlantic Ridge shown in Figure 1. Comment on the likely imp act of earthquakes occurring along the Mid-Atlantic Ridge. b Why do you think volcanoes are common along mid-ocean ridges? How would they be connected to the formation of new crust at these locations? c Conduct some further research into the formation of each of the following: • the Himalayas • the Marianas Trench • the Andes. In each case find out the plates involved, their characteristics, their direction of movement and the processes which occur at the plate margins. 3 Complete the puzzle on the right by finding (a) each of the words listed, and (b) the names of four of the plates of the earth’s crust (write these in the spaces provided at the end of the word list). ]fli I ë TE Y ~E T~ i ~i A RN S T L U A F E RA R E A AMG AM I T 0 N TSZS E I S S PACT H S C T 00MB L L K L QMARG I N S A P S E U U F E C E C R U S T F A RT S U RH T S C UT KEN S I T CEVNOC EMRO F S N A R T A F S NA I S ARUE S OL A F R I C A N S 0 C 0 C EPICENTRE ROCKS EARTHQUAKES CRUST SEISMIC MANTLE PLATES FAULTS TRANSFORM THRUST Magnitude Earthquakes with the greatest magnitude (amount of energy released) send out the strongest shock waves over the largest area. They therefore have the greatest potential to cause damage. However, big earthquakes often occur a long way from people and property, and so cause little or no damage. Timing The time of day and the time of year that an earthquake occurs may strongly influence its impact. For example (i) an earthquake striking the centre of a city may cause fewer injuries if it occurs during the night, and (ii) after an earthquake, winter conditions may hamper rescue efforts and delay repairs. Location The earthquakes which pose the greatest threat are those which occur in or near built up areas where population densities are high. Many of the world’s earthquakes happen under the sea. Often these pass almost unnoticed. Others occur in remote locations, such as deserts, where few people live. Tsunamis Tsunamis (often wrongly called 4tidal waves’) are huge waves which result from earthquakes (or volcanoes) under the sea. They are sent out from the epicentre, and grow in height when they reach shallow waters. Along coastlines they can cause more damage than the earthquake itself. Side-Effects The impact of an earthquake can be much greater if it triggers off other disastrous events. For example, a landslide may result directly from violent shaking of the ground. Fire is another common side-effect, as gas or oil from fractured pipes ignites and spreads. Buildings The collapse of buildings is often the most costly form of damage and the major cause of death during and after an earthquake. For example, impact may be increased by the collapse of unreinforced masonry walls and heavy roofs, or reduced, where buildings are of lightweight construction. Section 7 r~a. ~ R7 Earthquakes - Their Different Impacts Figure 1 7- / Factors affecting the impact of L earthquakes Activities 1 Using the information in Figure 1 answer the following. a Comment on how timing may have contributed to the impact of each of the following earthquakes: The Iranian earthquake of 1990 occurred in the middle of the night, demolishing 54 towns and villages. Most of the 50,000 people killed were farmers who spent their days in their fields. In 1983 an earthquake occurred in the middle of the night in the city of Liege, Belgium. Showers of stones broke away from buildings and fell to the streets, but no-one was killed and there were few reports of injury. Apart from timing, what other factors may have contributed to the impact of each earthquake? b Is it always true to say that earthquakes with the greatest magnitude cause the most damage? Explain your answer. c The Armenian earthquake of 1988, in which 25,000 people were killed, occurred in the middle of winter. Suggest one advantage and one disadvantage of the timing of this disaster. d In Turkey and Iran, traditional houses have mud-briOk walls and heavy roofs, while in many African countries local buildings are made of very lightweight materials. Explain the advantages and disadvantages of each type of dwelling in (i) protecting the buildings occupants during an earthquake and (ii) withstanding the effects of an earthquake. e Explain how (i) fire and (ii) landslides are common side effects of earthquakes. contd 4’.... C. .•• !ntraplate Earthquakes About 95 per cent of earthquakes occur atong the edges of the plates oV the eattWs crust. However. some earthquakes occur mn the iincñor of plates. These are caflcd intraplate eai-tbquakes. Thcy do not occJr ID well-defined patzcms~ like those at plait bcurtctaSs. and so they arc riot so ~ to explain. What is known ~Li.out iruraptaie earthquakes is that they: are caused by swesses in the crust to depths of 5(1km; can be i~la~e4 to sL1tssc~ at p~stte tioundarics and iempemwre changes hi the crust caused by processes deep in the earth; • usually inur uaexpcctadly. as it is at pre.stnt impossib{e Le predict their kcadoii. size or timing; • like other earthquakes1 do r~ot have to be of large magnitude to cause significant damage ~f they occur close tc a pepnlation cenlrc (eg Neweasile 1989).. In 1 9SS. a scñes of relatively large intrapi ate earthquakes (of up to 6.8 on the Richter Scale) occurred near Tennant Creek in thc !4ththern Territory. Located thousands of kilemewos from the nearesi plate rn.argin1 it was apparerscly caused by the release of stress that had built up in compressed rock only a few kilornetres below ttie Iamd surfnee. Figuic 3a shows how the shifting grciurId opened largc swface cracks, while Figure 3b shows a gas pipeline which was bent by the earthquake. Intraplate canhquakes can also be caused by the tilling of large dams, The waler in resen’oirs cau~~ an inn-eased lead on the earths crust, and, more iznpcriantly. causes il-ic wateitable In rise and lubricate nezarby fau1rs~ Secoon 7 ——= 88 Earthquakes - Their Different Impacts (contd) tWUTe 2 Activities (contd) I Conduct some research mb tsunainL~. Find out: • how they are formacl. • where they arc most likely to occui; • how they develop as they trawl away from the earthquake epicerthv; • the speeds and heights they reach in open water and they approach ~ shoriLinej • th~ impact they may have on people and property (including examples) 2 Read the inforntaUcn in Figure 2, and answer the fol%owirg~ a What ~tre ‘iritraplate ear thquakes2 b Why is it more difficult to predict the kgatierts of int-rapkite earthquakes than those that occur Flaun 3: 1hc irn~ncr ct the Tcnnarn Creek ctrthquakc. 19U a Ground rupnirc b A warped gas pipcL~nc at plate margixts? c Suggest why intraplate earthquakes would tend to be of lower m~tgniti~de than those at plate margins d Why do you thLnh the thiraplaic r~arthquake which .‘tntck Newcastte in 19~9, and mnsured ~Ul On the ltkhter &‘ali~, had Far greater imp~ct thai~ the bigger TermarLt Creek earthquake of ci The damage bill as a result of the tennaritt Cnek earthquake was estimated at 52.3 rrtil: ion. From evidence in Figt4re 3, what types ci damage woi.~ld have contdbutad ts this bill? F Fxplatin how the fflhir.g of large darns can causri intraplate earthquakes 1 Why do you think that, on average, Australian earthquake (i) occur less frequently and (ii) are less-damaging than earthquakes in many of our neighbouring Asian countries? 2 Why do many of Australia’s largest earthquakes cause little concern? 3 Study Figure 1 and answer the following: a How do you account for Australia’s relatively small damage bill from earthquakes, up until Newcastle in 1989? b Australia’s largest earthquake (Richter scale 7.2) occurred at Meeberie, WA, in 1941. Why is it given a lower reading on the Mercalli scale than Newcastle, which was only a Richter scale 5.6 earthquake? c Conduct some further research into (i) the Richter Scale and (ii) the Modified Mercalli Scale. For each scale find out: HAZARD DATA • Australia is prone to ‘intraplate’ earthquakes; those that occur away from plate margins. • Historical records show that earthquakes occurred in most states during the first 50 years of European settlement. • In the last 75 years there have been 17 earthquakes in Australia registering 6 or more on the Richter scale. Some of the largest / most damaging are shown in Figure 1. • The western and central parts of Australia are the most active earthquake zones (Figure 2), but many of the bigger quakes have occurred in unpopulated regions and so have caused little damage. • In built up areas, Australian earthquakes have caused significant damage. However, they are, on average, of smaller strength than the world’s most damaging shocks. • Until Newcastle in 1989, the earthquake damage bill in Australia had also been comparitively low. adapted from ‘Hazards, Disasters and Survival’, Natural Disasters Organisation, i992. where and when it originated; Year Location Insured Damage/Remarks 1892 Launceston TAS 6.9 VII Unknown/offshore epicentre 1897 Beachport SA 6.5 VIII Unknown 1902 Warooka SA 6.0 VII Unknown 1903 Warnambool VIC 5.3 VII $0.39m 1918 Bundaberg / Rockhampton QLD 6.3 VII Unknown/offshore epicentre 1935 Gayndah QLD 5.7 VII Unknown 1941 Meeberrie WA 7.2 VIll Unknown 1946 Launceston TAS 6.0 VII Unknown/offshore epicentre 1948 RobeSA 5.6 VI Unknown 1949 Dalton-Gunning NSW 5.5 VIII Unknown 1954 Adelaide SA VIII $78m 1959 Berridale NSW 5.3 VII Unknown 1961 Robertson-Bowral 145W 5.6 VIII $3.7m 1968 Meckering WA 6.9 IX SlOm/16 injured 1972 Wilpena SA 5.3 VII Unknown 1973 Picton NSW 5.5 VII $2.5m 1979 Cadoux WA 6.2 IX 59.Sm 1985 Lithgow NSW 4.3 VII $0.lm 1988 Tennant Creek NT 6.8 VIII 52.3m 1989 Newcastle NSW 5.6 VIII $l,000m/13 dead, 150 injured (I) Richter Scale: Note that energy of a magnitude 6.0 earthquake is about 30 times that of a magnitude 5.0, which is 30 times that of a magnitude 4.0 and so on. (2) (Modified) Mercalli Scale: This scale measures earthquake intensity by rating the amount of damage caused. Roman numerals are used at each level, from I = a barely detectable tremor to XII = a major catastrophe. Section 7 r~.t 89 Earthquakes in Australia Activities who devised it; what it indicates; its upper and lower limits; who makes use of it. Figure 1 Some largel damaging Australian earthquakes over the last 100 years adapted from Earthquake A wareness for Australians’, Emergency Management .4 ustralia. / 994. coatS II\ 9* N. C- *~1 Activities (contd) 4 Using Figure 2 describe the distribution of areas with a high earthquake risk in Australia, Comment on the likelihood of serious earthqtMke 4anvag.~ in thi; an!as you have descnbed~ 5 a Using ar atlas, mark Meckerrng in Western Australia on the map. Figt~re 2. b Corrunent on the earthquake risk in the vicinity of Meckering c Read the ir&Iorrnation in Figure 3. Why dc~ v<~iu think no-onc w~ss killed in the large eathquake which struck Meckenng in 196S? 6 Study the photo graph thgure 4. What evidena~ from the photograph suggests th4t the earth moved both ver-ticalty and lalerally (ic- skI~ways) during the eaflhquMc~? Figure 4t Damaged railway Lines after the Mrckertrig eai-thqtiake, 19~S The Meckering Earthquake, 1968 The Mei;kerii4 earthquake possibly affected s ‘~der am of Au5aralia than any other in recent hisiory. Rr-sidents reported sedng the grricjnd buckle, as well as experiench~ cteeiing difliculuts WIWITL drivii~. Mta.saring 6,9 on the Rickiier Scale, the quake dairiaged ~COO buildings as well as destroying p~pelines, roads and railway Tines (Figure 4). The total damage waS c-stirtnted at abcut $40m ($ Him insured ~esses). however only 16 minor ~ijuric~ were repat-ted. Figw~e3 go Section 7 -~ ~_.._• - - — _Eanhqira*es nrr_ -. - ir Earthquakes in Australia (contd) P ~ ~ ~Qj ~me\ i1J~fl, Va—.J 4 CnIoi~r maebci iMitate the ~tfr~tstS ~f~thm.(id~d r~Id • ~‘-( ‘n~a~isI ocr to Mfltng as atkq~tb) with a IQ% thanr~ ~be~ rrcnW PM W yws SS&n~ dAmap Figun 2~ uswWv sin to st the C105 Set ~ Tht &igIra ths contaw t~Fia, the har~rd map ~ ~vt~tr1&put~Utffnrqafl*q~skn AusItai~a Esnhqnnke damage to the Kail Motel. Newpa~le The; Newcafll~ Workers Club after the eaithqualre Sect~on 7 ——La: 1/i P~ttk ~‘ 91 Case Study: Newca stle, 1989 WHAT HAPPENED At 1027arn On D~ccrnber 28! 19S9. Newcastle. Auswalia’s sLxtl~t largest city was devastated by a modente earthquake measuring S.6 on the Richter ScaTe~ The enthqualce dispelled the myth that Ausualia woukt never experience an earthquake of d~s~strous propoctions~ L~ves were lost and buildings dcsrrryed, as the grotrnd mellon waS magnified by the thir layer of aIILIVILIIII tieder!yctg the city. The cpicemre or the earthquake was Iccaled ~5Icn WSW of the ~iEv centre. ne-ar Boolarno. iNITIAL CONFUSION Newcastle was in chaos immediately foflowing the earthquake a~ office ~uS ctnt of buildings tnto rubble- strewn streeu. Police cordoned-off city sireets and evacua1t~ buIldings in the central business district. Dts~aster respc~rtse was hampered by a c%isnipted telephrne service. damage to criOca~ bw}clinE and hkeked road access. BUILDiNG DAMAGE Several hospitals were ~eriousEy darnagrtt causing chisniptIrm to medical SCTVJCCS and evacuation of patients~ I 4~ schools Were daitagcd Lfl some way. with three cleenwd utisuftable lot us-c. ~n aD. 35.000 hurries anti 3AX1 other buildings were moderately to seriously damaged. with oldcr buFidiuga sutfenng the mno’it itt all. insu-red 1osse~ were about $1 bthlion. GEOLOGY AND EARTHQUAKE IF1STORY Newcastle etperic need an ~ earthquake - one which occurs aw~iy from the piate rttargins of the carths ernst Where such eanhquakes are likety to occur and how they arc caused. are at present poartv understood The 1939 4uake struck wdli out warning in what was considered a low-risk a,:a How~er. there Imad hccn Six relatwely large eclrthqthâes (RLhtef scale 4.5-5.5) rep-oned hi the Hui-iter VaLley region S ince 1829. DEATHS AND INJCRIES There were I] &aths and 1511 injurhis. At the Kent Hotel three fatal ifies iwcurred, whtle mi ocher fltflC re-suIted frotit the collapse of the Newcastle Wl)rkcrs Club (see pheic graphs abovc) Three floors of the cluh’~ weslern v, ~ collapsed duting (he earthquake, trapping i-nan> peopLe. As a re~ailt of daina~e Ia hos~iiiiml.s. nlediLaE scrvices were strmiied to cope wflj~ uhc dmsasLn AFFECTED AREA The effrcu of the Newea~jtle eanhquakc were felt up to 550km from the epicentre i~e.g to the north at Cuffs Harboor) The shaking lasted shout six seconds En Newcastle, with the area sufferrng structural damage extending to Liverp-oot (Sydrieyi in the south (l38krn)~ Scone in the north-west (145km). and Gladstone in the north (320km). The damage ~ seleciive with the major contributing r~t~ being the alluvial ~edimcnts on which many buildings were situated EFFECTS ON lAND There were several reports of people ~ecing eanht~tiake waves travelling across the ground. 1-lowesrer there was no evicknce of ground deformation. surface ruplurcJlaliIung. 014nc subsideuce or hquefacrien. Unlike other earthquakes, r~s were not one of the damaging sida-effacts in Newcastle. Only otic firt Wmt’~ reported alter the earthquake EFFECTS AT SEA Unusual happenings at sr-a in the Newcastle area we~c reporte± Several large ship-c east of the port of Neweasde, arid heats on lake Macquaric re-ported high-frequencry ‘iLbraiians of the vessels at the time of the earthquake. Suriboard riders at beaches reported Ewe large ______ waves appearing out of a fairly cairn ç~ee~p• and sea tkxr movemenn Wete reported by skin divers ~thipre4from ~irffiq#~g A ~ren4n frr Aj~sJroIiar’~ E~tdrgeacy Maaa~e4nnu Auarclia /~94 Figure 1: J~aturcs or the Ncwca~iIe cirthqtiakc 19S~i Figun ~ Rescue we4rtc ai iS damaged Neweailc RSL Club Figure 3; Resete opemttogis in tile Newcastle ~ Club Case Study: Newcastle, 1989 (contd) to occur during ur after a major Activities I Using (he infamiat ion ia Figure 1, answer the following: a What is meant by the ~epicentre’ of the earthqtiak& b How did the tocatLari of the epieentre contribute to the Newcastle earthquake bc’rorning the most damaging itt Australia’s histcry~ c ~indoutwhatJs rnearitby ~a thin layer of alluvium’. low did the presence of 0-us ‘ayer beneath the city contribute to the seventy of the Newca~tk earthquake? d Conduct sortie research to find out~ • what is meant by art~Lntraplate earthqt.aake’, • how intraplate earthquakes differ from those that occur at plate margins; • why little is known about where they am likely to occur and how they are caused. e Do you thirtic Newcastle should have been cons~d€red ~a low risk area’ for earthquakas before 19897 rxpiawt your answer. f-low would you describe the earthquake risk in Newcastle in lig.hL cil the 19S9 experience? f The Newcastle earthquake showed ‘i-to evideric-e of ground deforniation, ~urfa-ce rupture/fau1nng~ mine subsidence Or liquefactton# • What is meant by ~ground deformation’ and #surfacv ~ What dor~s the absence of these two effects suggest about the Newcastle earthquake? • What is ‘mrrie subsidence’? Why is it likely eaflhquake? What are some of the likely hazards related ti~ rnia-’ie subsidence? • What is liquelachon’ and how is it related to earLhquake activity? What ,~t? some of tha hazards which could be Caused by liqudadien? g What were the main causes of death and ui~ury in the Newcastle earthquake? 2 The Newcastle earthquake occurred mid-morning on a business day in the school hoildays. Do you think the timing ci the carthqnako would have (i) contibuted to the death and injury toll, or ~ii) helped reduce the death and injury toll? Explain ~Ot]r answer. 3 Imagine you were in the centre of Newcastle at lCL27am on December 28, 19S9. Describe; • how you first recagrnsed that an €arthquak~ was occurringi a the activity you were participating in at ti-se time of earthquake, and how this was Mfrcted; • the inunediate effects ci the earthquake on your surroundings; a your observations of noise, human behaviour and impact on lives and property, • your ths.eniataori of (he search and rescue operation lollowing the earthquake, rrEclucling your pact in the operation: • the tong term effects of the earthquake on tbr~ city of Newcastle and 1(5 people. bay. 1993 HAZARD DATA + Tsunami is a 3apancse word meaning !waves of the • A tstmam~ i~ actually a series Lif travelting ocçarn waves o1e~aremeFy long length and tong wave period Tsurbarnis are caused by earthquakes (or volcanic eruptions) beLow or near the ocean floor. Waves are sent out i~ all dire-ctgjns. much 1]kc the effect of drcppitig a stone into a pond. • As a tsunami ciosses a dccp occat1 it may travel at speeds exceeding 1000km/h. its length from crest to crest may be I 50km or more, and yc~ height ma~ only he a mc~tre Ii is not felt b) ships in deep water arid cannot be seen from cite a’r, • As a ~ enters shallow wiuet neSt a coai.stliii’e, it~ wave speed drops and a~ lie;ght increases It can reach hei~hts of 30 to 50 mcun arid sthkt with dcvastatthg force, oftcn diou sands of kilorriotres from the earthquake or volcano which caused it • The mejoncy of tsttnarnis ~ in the Pacific Ocean, a1thoug~ theit have been reports of tsiuiar&s in alL ~tans of the world • The tsunami threat to Austra1~a is very slight chic to the protection from South West Pacific IslaMs and the Great Ranier Reet Mzpith from H~z2rdy, Fknuerc and SwvJvd, Nawr~i1 thsasrtn Oz-~Umfosnn, 1992, direction of tsunami low beigta(eg. metz~)n1npid tin&rwater speed {eg. ~ lXlOkmIh) in deep water earthquake On reaching shallow coastal wiiter speed ‘frcreases and height increasn (e.g. 50 metres) Secitc~n 7 — - _____ — — — —- — ______ b The niJage in Ftgure I had a breakwater af(ected arid its ~mpact on liVL•s and property. Ts zinainis :.‘~~1’~ Figiirr 1~ Tson~nlL ilamage ~c, (he ~i!Iagt of Kptatiiy~mz~ attrr the Htkka~do-Nansei-Ckt t?~snbquake, Figure 3~ T~urntrn fiwm~i bfl Activities I Ustrig the rnFormation in ‘Hanird Data’ and in figure 3.~ tlescnbci how the characteristics of tSuflatThs between when they are formed in deep ocean waler arid when they reach the shore. 2 a Front the evidence in Figure 1, list 5 different ]rt~p4cts ot tsunarr~is which would not othenvise be associated with earthquake activ;tV Figtire 2: Tswiami ~ippro~ches the diorii m Hach] priori, hpan, afur the Nthon-Kat-Chubci ranh~uake~ t9t~3 protecting it from tsunami damage. Comnuent on its ellectiveness. c Figure 2 shows a tstrnami approaching a protective wal] on the shore. How is the walL cksigrted to reduce the ünpact of the wave7 3 Conduct some research into the world’s worst tstmaxnt disaster - Krakatoa. 1R83 Find out the cause nf the tsunami, its characteristics the area it Build on suitable ground I-lard rock is best. Soft areas of sands and silts should be avoided as buildings are inclined to sink into these, particularly when they contain a lot of moisture. During an earthquake these soils also act like jelly, amplifying the shaking of the ground. Avoid artificially filled areas, as these often provide poor foundations and may experience greater shaking than natural soils. Chooss~ the right materials.~ Matenals can be chosen for rigidity, to resist disintegration, or for flexibility, so that the building bends but does not break. Elastic materials, such as wood and steel, are the most earthquake-resistant Unfortunately, in swaying to and fro they may damage or knock down adjoining buildings. Brick walls are likely to buckle easily, and so should be given additional vertical support. Make the building solid Strong foundations should be put down and load-bearing walls solidly fixed to them In turn, the roof should be solidly fastened to the walls. Walls should be reinforced Concrete walls may be braced (e.g. with horizontal and vertical steel rods or by cementing wire mesh into them). The building should be square or rectangular in shape. Ensure maintenance of old buildings As buildings detenorate during their working lives, it is important that regular maintenance takes place to ensure standards of earthquake- resistance are maintained. This may involve replacing mortar which has deteriorated or fallen out from between bricks, installing new bracing between walls and replacing rust-affected or fatigued metal components. Section 7 94 Earthquake-Resistant Buildings Figure 1 N Earthquake-resistant building principles 7 / N Activities 1 Study the mformation in Figure 1 and then answer the following: a Why should areas of sand and silt be avoided when choosmg a site for a building in an earthquake- prone area7 b In the San Francisco earthquake of 1989, the expensive Marina Distnct, built on a landfill, suffered the most damage and also experienced more severe shaking than many areas closer to the epicentre How do you explain this’ c Describe one advantage and one disadvantage of usmg flexible materials, such as wood and steel, when building in an earthquake-prone area. d What does it mean to say that brick walls ‘should be given additional vertical support” e The cementing of wire mesh into concrete walls to make them more earthquake-resistant has been likened to the laminating of a car windscreen. Explain the similarity. f Explain why square or rectangular buildings are most likely to resist earthquake damage? g In the Newcastle earthquake of 1989, building damage was confined almost entirely to old buildings. Suggest at least three reasons why this might have been the case. 2 In Newcastle, the the posts supporting awnings above many shops were replaced during the 1950s by tie-backs fixed high on the front wall Why do you think this was done? In the earthquake of 1989, many of the facades (fronts) of these shops suffered severe damage. Explain, using a diagram to help you, how this damage could be linked to the way the shop awnings were supported. 3 Conduct some research into the Mexico City earthquake of 1985. In particular, find out how the following factors contributed to the damage caused. The quality of building construction in the the Zona Rosa (the city centre). COlT iall building with exira reinlc•rcemerii at ihe joints allowing ilexibiliiy Figure 2: Earthquake-resistant high rise buildings (Dolan, C. Hazard Geography. Longman Cheshire, 1994) Section 7 Earth quakes 95 Earthquake -Resistant Buildings (contd) Activities (contd) • The type and density of buildings inthe Zona Rosa. • The level of upkeep and maintenance on buildings in the Zona Rosa. • The type of soil underlying Mexico City. 4 Study Figure 2, and answer the following: a Describe the different earthquake-resistant features in the two high rise buildings shown. b How are the differences between the buildings related to the type of ground on which each is built? c After the Armenian earthquake of 1989, Geographical Magazine provided the following explanation for the extensive damage to the town of Spitak: The destruction and loss of life in the Armenian town were increased by a very low quality of construction, with the use of sub-standard building materials, skimped and adulterated cement, with faulty and badly supervised building techniques a prefabricated-panel type of construction has been used in all of the hundreds of thousands of apartment blocks built in every tozon across the USSR, including those within the regions subject to earthquakes. In the recent disaster, such prefabricated blocks collapsed like packs of cards. List four design or construction problems which contributed to buildings collapsing ‘like packs of cards’. With the help of Figure 2 make a list of the earthquake-proof design and construction techniques which could be used in the rebuilding of Spitak. 5 As a result of the Newcastle earthquake of 1989, a local building company has shown interest in incorporating earthquake-resistant features into their homes. As a well respected and highly qualified housing consultant, you have been asked to design an earthquake-resistant house which can be used for display purposes in the Newcastle area. Using the design principles outlined in Figures 1 and 2, sketch your house design. Use labels to highlight the main design features. Across Down Section 7 .Earthauakes 96 Crossword: Earthquakes 5 Famous fault line which runs along the west coast of the USA (two words). 6 The point on the earth’s surface which is directly above the focus of an earthquake. 7 Instrwnent used for measuring and recording earthquake shock waves. 10 One of the largest plates of the earth’s crust. 11 Scale used to measure earthquake magnitude. 14 A measure of the size of an earthquake. 17 This Australian city suffered major earthquake damage in 1989. 19 The of buildings is amajor cause of death during and after an earthquake. 21 The point of origin of an earthquake. 22 A common side-effect of earthquake activity, often caused by the rupturing of gas pipes. 23 Earthquake damage is usually greater in_______ than in rural areas. 24 waves are sent out from the focus of an earthquake. 1 Suppliesof maybecutafteran earthquake. 2 The layer of the earth beneath the crust. 3 Earthquakes which occur under the — — — can cause tsunamis to form. 4 One of the most earthquake-prone countries in the world. 8 Segments of the earth’s crust which ‘float’ on the heavier, semi-molten rock of the mantle below. 9 Accurate ofanearthquakecan greatly reduce its impact on people and property. 12 The outer shell of the earth. 13 Huge ocean wave nomally caused by an earthquake under the sea. 14 Western Australian town which experienced major earthquake damage in 1968. 15 Earth usually result from minor earthquake activity. 16 Ground is a common side-effect of earthquake activity. 18 Process where plates collide with each other, move apart or slide alongside one another. 20 City suffered major earthquake damage in 1985. In this section 98 99 101 102 103 105 106 107 97 Section 8 The Volcano Hazard Page • VoIc.~nnc~ Glossary of Key Terms a What is a Volcano? • Flow Do Volcanoes Form? • The Destructive Effects of Volcanoes • Case Si udy: Mt flnatubo, the Philippines. 1991 VolcanoesBenefits arid Attractions Predicting Volcanoes • Repo:ting L)isasters: R~~baul Volcanic Eruptions, 1994 98 Volcanoes: Glossary of Key Terms Active volcano: Volcano which has a history of regular eruption (e.g. Japan’s Mt Aso is the worlds most active volcano with 162 recorded eruptions). Caldera: A collapsed volcanic cone. Composite volcano: A cone-shaped mountain built up by many volcanic eruptions and consisting of layers of lava and ash. Cone: The hill or mountain built up by the deposition of volcanic material. Crater: A circular depression around the top of the vent of a volcano. The crater forms the summit of most volcanoes. Cinder cone: A steep-sided, cone-shaped hill built up by cinders (fragments of solidified lava) ejected from a volcano, Cinders: Fragments of solidified lava. Dome volcano: A tall, convex-shaped volcanic cone formed by thick and treacle-like lava cooling quickly and so not flowing far away. Dormant volcano: Volcano which has erupted in the past, but has been inactive for a long period of time (e.g. Lassen Peak, USA). Dyke: In a volcano, a vertical intrusion of magma which forces its way towards the surface through cracks or openings in the crust. Extinct volcano: Volcano which has been inactive since the beginning of recorded history (e.g. Mt Kilimanjaro in Tanzania). Lava: Molten rock which has flowed from the interior of the earth onto the surface. Magma: Molten rock below the earth’s surface, held in the magma chamber. Shield volcano: A broad, flat volcanic cone formed by runny lava coming slowly to the surface and spreading widely before cooling. Sill: A horizontal intrusion of magma which forces its way between layers of rock. Tephra: Solid materials in various sizes which have been ejected from a volcano during an eruption (e.g. ash, ciders, lapilli and volcanic bombs) Vent: An opening in the earth’s crust through which volcanic material flows. Some volcanoes may have a single central vent while others may have a number of smaller vents, called subsidiary vents. • ..:~. ~ ~. crater cone .,__,,,,~ lava various materials ejected during an eruption, including molten lava and tcphra (i.e. solid materials such as ash, ciders, lapilli, dust and volcanic bombs) ~,~subsidiaiy vents F,— magma chamber containing molten rock Dome volcano A tall, convex-shaped cone formed by thick and treacle-like lava cooling 9uickly and so not flowing far away. Shield Volcano A broad, flat cone formed by runny lava coming slowly to the surface and spreading widely before cooling. Composite Volcano The most common volcano. A conc.shaped mountain built up by many eruptions and consisting of layers of lava and ash. Figure 2: Types of volcanoes Cinder Cone A steep-sided, cone-shaped hill built up by cinders (fragments of solidified lava) ejected from a volcano 99 Section 8 Volcanoes What is a Volcano? Figure 1: cross-secwtn through a volcanic cone COPI (LI What is a Volcano? (contd) Figttn! 2, volcAno ifl the Yigksre 3: The masswe ash~ ruck and sceam cniprirrn oF Mi St Hekns. USA. i980 Liii ‘fl (9 ‘~ ji) h;tiL 111 I)III~1. TN Oil! t brM P~O~ S. I H TP A C I N M S U D~E~R ELD I TiES U~RE SIRC nO TN AD E~ERA AYCR AMJALY L~H S 9 10 C[NI1LL If PA L Voicanon 100 Activities 1 Using the Lnformaticrt provided in construct diagrams of each type of space provided On each dia~ram • ‘abel vsd, era~e-r, magma resen’eir and CfllE, LLSLThg Figure 1 to help you; • add shading and additional labels to show particular characleristics of each type. 2 Study Figure 3. and complete the following: a Write a brief description of the eruption scene shown. b How would you account for each of the following des!nictive effects of the Mt St H€lens eruption of 19S0 • The collapse of houses and other building. • Mud and rock ~val~nches on the sides of the snow-covered volcano. • Widespread flooding of riwrs, • r!att~fr~g of forests. • Loss of animaL fish and insect life, c How wotild you classify Mt St Helens usmg the types of volcanoes shown in Figure 2? Give reasons for your answer 3 Complete the puzzle on the right by adding the missing words to each of the Following dues, ad then finding the words in the puzzle. Clues 1 Molten rock underground is called______ 2 The lstheopertirtgatthetopofa vokana 3 Duringan_.__ lavaandashmaybe ejectS from a volcano 4 A — — cone may appear on or close to the main cone of a vo1cano~ 5 The - - - is apen4ng in the eaxtWs crust through which vokanic material flows- 6 The magma — — — - - holds molten rock below the earth’s surface 7 A — — — ~. — .~ — volcano consists of layers of ash and lava~ are fragments of solidified Iai,a. A volcano is broad and flat. Small tragrnents Or rock ejected from a volcano ate called 11 Vokanic are large rocks ejected from a volcano. 12 Composite vokanoes are the must -. — - - — type of volcano. 13 In the Mt St Helens volcano. tonnes of — — — wcre dumped on the surrounding countryside. 14 Dome volcanoes are in shape~ BX C~AEE1OPit VJMB S HSRHR E.Z NML A]V00 AIMIG 0 M 0 N 15 fri a composite volcano. — of ash and. lava are deposited during different eruptions~ 16 The mountam Or hillside formed by volcanic action called the 17 Molten rock which flows Over the eart.Ws surface during volcanic activity Mcd~ th A — — — volcano is funned when Duck lava cools quickly to form a talL convex cone. The remaining letters form a word which describes all solid material ejected Etcun a volcano; ocean trench A - ~-c~ ~t~• ~:‘ 1. Ala destructive margin one plate dives beneath the other. Friction causes 1110 men and become molten magma. The magma forces its way up to the aurlece to form a volcano to the aide of the actual plate margin (the ocean french(. A nunter of volcanoes may react the aurtace to form a string ot ialanda catted an taland arc e.g. the Philippines. 2. In places where a plate ia particularly thin magma may be able to acape to the surface. Such a piece Ia catted a hot spot’. Aahield vclcano wilt be termed like those on Hawaii. 3. Where two plates era moving apart new magma cen reach the surlece through the gap. Volcanoes forming along this crack create a sLbmarne mountain range catted an ocean ridge e.g. Mid- Atlantic ridge. 4. Sometimes deatrucfive margins invoive continents. Instead ot lorrning islands volcanoes occur within a renge of mountains e.g. Andes. Section ~ Volcanoes 101 How Do Volcanoes Form? Figure 1: The formation of volcanoes (adapted from Dolan, C. Hazard Geography, Longrnan Cheshire, 1994) Activities 1 Obtain a copy of a map showing the plates of the earth’s crust (one can be found on page 85 of this book). Using this map, and the information in Figure 1, answer the following: a Explain the formation of the following. • Volcanoes in the Andes mountains, along the west coast of South America. • The Mid-Atlantic Ridge. • Mt Fuji in Japan. b Iceland is one of the most volcanically active countries in the world. Explain why vocanic activity occurs so frequently in this country. c Find out where the ‘ring of fire’ is located, and why the name is given to this region. Would you include (i) Australia and (ii) New Zealand in this region? Explain your answer. 2 Using information in Figure 1, answer the following: a What is a ‘hot spot’? How can volcanic activity on Hawaii be linked to a hot spot? b Explain the formation of island arcs, such as those found in the Philippines. c What are ‘ocean trenches’? Explain their formation. Why do you think ocean trenches are found close to very active volcanic regions? 3 Match each of the following statements to one (or more) of the formation processes (i.e 1, 2, 3 or 4) in Figure 1. • Submarine mountain ranges are an associated Iandform. • Gentle eruptions are most common ~f magma reaches the surface. • Explosive volcanoes may occur to the side of the actual plate margin. • Friction causes plate material to melt and become molten magma. • Likely to occur where plate material is particularly thin. • Occur where plates are moving apart. • Result from continental plates moving against each other. • This formation process occurs at a constructive plate margin. VOLCANOES: Range of destruction \Tolcanoes can he dangerous, not only to their immediate vicinity, but also to areas further afield. In the immediate area, main dangers come from blast effects, lava flows and volcanic earthquakes. Ash deposits and tsunamis can cause hazards much further away. Compared to many other kinds of disasters, the death toll from volcanoes is relatively low, depending on how close people are to the volcano, and how many people live in the general area. The destructive power of volcanoes is immense, however, destroying whole villages, crops, forests, roads and often creating a large number of evacuees who have to he sheltered, fed and eventually resettled. There is an added danger too that lava flows may distort the natural contours of the land, fill in water courses and cause floods, mudflows and landslides. A great deal of research has been done on volcanoes and in many countries, active and dormant volcanoes are being monitored to note any changes in levels of activity, In this way scientists hope to give people greater warning time if eruptions are likely. front ‘Hazards, Disasters and Survival’ Natural Disasters Organisation, 1992 IDS E Section 8 Volcanoes 102 The Destructive Effects of Volcanoes Figure 1 Activities Fill in the blanks in the following sentences using information in Figure 1. Check your answers by finding them in the puzzle on the right. 1 These huge waves can result from volcanoes under the sea: 2 Volcanoes cause the destruction of and 3 Two associated effects of volcanic activity, particularly on steep slopes are and 4 If the — . — of the land is altered by lava flows, can result. 5 Two types of material commonly ejected from volcanoes: and 6 Volcanic eruptions can force the____________ of large numbers of people. 7 A volcano with a history of regular eruptions would be classified as S Volcanic cause shakingofthe ground. 9 The — _ . -- toll from volcanoes is — — — compared to many other types of disasters. 10 villages can be destroyed by volcanoes. 11 Ash can be carried great distances by the — — — 12 The death toll from an eruption depends mainly on the size of the living______ to the volcano. 13 Two of the basic needs of evacuees after a volcano: and 14 Eventually, pcople left homeless after a volcano will need to be — 15 If lava flows alter the slope of the land, may flood. T L~ A N D S L M S L 0 P E El R P0 DE SE VA U P U T C M UI D 0,1F~R]DLC F N1E 0A 1T 0H V P1LEU~li L T K CA UUA1 V S M W 0 C A L T W I S A E Q. T W L C F 0 R E~S T S H 1 5 0 T L F 0 0 II I E T 0 A S I W I N B E 0 R R J N Eu VE R 011 A~ 01S~iE: NOL~1 A J Nif~I 16 Tsunamis are most likely to affect people living on the 17 If scientists can predict eruptions it will give people more warning — — — — The remaining letters form a word which desribes the forcing of materials through the vent of a volcano and onto the earth’s surface. Ash deposUs cause huifdthgs to co//apsi~ ~es~fu1ricthn Pinawbct showed uts lirsi signs of awakening back an April, a’ smaLl sicam eruplions drew local scientists and vulcanologisls from Ike liSA to the rnounEain, This joint team, which sU up a monitoring slalion on the volcano, is now credited with predicting the major eruprtons of the lasi month. Section 8 —.Vo/canoes I cii Case Study: Mt Pinatubo, the Philippines, 1991 - The big one: Pinatubo’s deadly eruption ‘Thousands of people fled as Mt Pmatubo, ~o the ~rnrth-westcrn lThihppiries, again explc4e4l into ?Jfb yesterday. The latest, and biggest exp]osion yet, set off deadly pyroch.stic flows (clouds of white hot dust and gas) and ejected red hoc tephra ranging from grapefruit-size vo!canic bombs to tine panicles of ask Mudflows ialler than houses swept down valleys, as he-avy rain combined with the tonnes of ash dumped on Ihe sides of the nrnniain Earthquakes followed the erupdon as parts of the mountain collapsed into the caverns left by escaping lava. By mid-afternoon the sky was black as nigh. as far south as Msruta (85kiTI away~, a~ ~ relenitess ~iaiif o purrtk~ pebbles poured down, wji Etc thunder and lightning from a tsopkal storm alternated with brilliant orange f1a~tht~ from the volcano. Dormant for more than fi00 years, Mt Piriawbo has n(}W extracted a terrible toll during the &adly erupuons of the last monTh. Over 700 people have been ki(led and 42,®0 homes hava been desiroycd. as mbdFtUWs have wrecked foothill vi]lage~ and •he weight of ash has collapsed flimsy houses Another miflion people have been f~ced to flee their honies and 40000 bee tares of cropland have been buried by ash. Ther prcthciirns were based on a range of IieW and irripmved lechniqotis dcs]gned to give warning of’ ike movement of hot, mt)(i~J-I nick (called magma) beneath the ground surface These teehn]ques iricludet • seisuiometers linked to computers to accurately detect earth tremors caused by magma movement below the land sur1ace~ • special sound eqLiIpmcnt~ again linked to computers, to JcEccl the tow nirtb[c assoc~ated wtth magma movng op the vcmtt of the V&LaFW; • iilurieters to detect cvt~n the sLightest change EU the ground surface caused by pressure froni rEs]ng magm a; • pollution detectors, 10cc those mused on factory chfrnneys. uiscd to measure sulphor emissions - a si°n of nsing magma. Mt Pcnarubo The restili of successful prediction has been a death ejects a c/oud toll far less than expected from such major eruptions of gas and Locals have heeded the warnings of sciencisis and ash evacuated Hi hi4ge nomhers 10 safer ground fri The Atmospheric Effects of Pinatubo Mt flnarubo’s maesive cruption was the largest on record in the Phdippines and On a world scale, produced the largest cloud of climate-modifying gases since mnighly Krakatoa ci-upted in Indonesia in 1883 The cnipiicin of Mc P~naiubo, Juruc 1991 Scientists estimated ihal Prilatubo s ecp]osion added imire aei-unols (light gases and particles) ihan all man-made ~greethousc gases’ since the Industrial Revolution began! An average reduction oIO5’C to the eank’s tcmnpcrature was rticorcktl by satellite within months of Piriawbo’s eruptioni and w]Ihin a year, a fall of one degree was noted. This cooling effect was expected to persist for several years, not even allowing for possible future similar eruptions by Panawbo or other volcanoe& &apiedjmm ‘Hurjn-ds. Ths asIer~ aid SurWvaI’) Naiuraf Drsa~uers OrgwiL~a&in, 1992, Se.::rkii~ ~ -. Vdcwwes 104 Case Study: Mt Pinatubo, the Philippines, 1991 (contd) Activities _____ I Using the information and photographs in Figure I, answer the following: a What are ‘pyroclastk flows’? Suggest some of the damaging effects which may result from these flows. b Explain the tonnalior. of the following durLng the major eruption of Mt Pinalubo: • huge rnudflows; • earthquakes. c What are ‘pumice pebbles’? Ilow are they formed? What uses can be made of pumice? d What does it mean to say that Pinatubo had been ‘dormant’? How is a donnant volcano different from (I) an active arid (II) an extinct vol earto? e I-low did the sqccessftij prediction of Mt Fthattibos eruption help reduce the death toIl which resulted? f Thtplain in your own words how each of the following pieces of equipment were used to help predict the eruption of Mt PthaUibo~ • seismometers sound equipment • tfltmelers • pollution delectors. 2 Using the information in Figure 2, explain how the gases from the eruption of Mt Pinatubo could contribute to a reduction in the earth’s temperature (construct a diagram to help your explanation). FIgure 2 Religion The word volcano comes from Vulcan, the name the Romans gave to their god of fire. This ancient link between volcanoes and religion remains a central part of many people’s beliefs. In Japan, thousands visit Aso, the most active volcano in the world, every year to pay homage to the god that the volcano represents. In some of Indonesia’s volcanically active areas, locals still believe that they will be protected from a major eruption if the gods are appeased with gifts and sacrifices. Fertile Soils Deposits of lava and ash, when broken down. enrich the soil with phosphorous, potassium, magnesium, calcium and sulphur - the major elements required for plant growth. This makes volcanic soils some of the most fertile in the world. For example. on the island of Java in Indonesia, rice farmers can harvest up to three crops a year in the dark, rich volcanic soils. Here, and on other volcanic soils, some of the most densely populated farming communities in the world are supported. Industrial uses • Sulphur deposits are used in the chemical industry. • Basalt. a hard volcanic rock, is widely used in the construction of roads and buildings. • Volcanic ash can be sold as fertiliser, or may also be used as a building material. • Pumice, a natural glass that comes from lava, is used for grinding and polishing stones. metats and other materials. It is also used to remove stains from the skin Hot water and Electricity In volcanic areas, where magma is close to the surface, underground water may be heated to 2000°C or 3000°C at depths of only 1 to 2 kms. Boreholes can be sunk to tap this water and bring it to the surface as a mixture of hot water and steam. Here the steam can be piped to power stations for the generation of electricity, while the hot water can be used for heating. This geothermal energy already makes an important contribution to the electricity supplies of New Zealand, Mexico, Iceland and Italy, and has the potential to be used in many other countries. Section 8 Volcanoes 105 Volcanoes: Benefits and Attractions / / /, The attractions and benefits of volcanoes / TourismVolcanic areas contain some of the world’s most famous tourist attractions. For example:• Beautiful volcanic peaks like Mt Fuji in Japan and Mt Kilimanjaro in Tanzania .• Unosoal and spectacular features like the Old Faithful Geyser, USA, the hot springs of Rotoroa, New Zealand, and the caldera of Santorini, Greece.• In Australia, sites like the Blue Lake in South Australia, the Glasshouse Mountains in Queensland and Tower Hill caldera in Victoria Archaelogical significanceFor archaeologists, volcanoes are very significant because of the way they preserve the past For example:• In the faiiious Pompeii eruption of Al) 79, sudden falls of volcanic ash covered the city and preserved everything in place for thousands of years.• Akroteri, a once thriving seaport on the island of Santorini, was buried for about 3,500 years before being uncovered again in 1967. Here archaeologists found houses, weapons, pottery and precious metals perfectly preserved. Activities Figure 1 1 From the information in Figure 1 , explain why some of the most densely populated farming areas in the world are in volcanically active areas. 2 Conduct some research into the following: The generation of geothermal energy (electricity generated from underground sources of water and steam in volcanically active areas). Try to find out: - how the electricity is generated (use a diagram to help your explanation); - the advantage(s) of geothermal energy over eleetrieit~ from coal bummg power stations; - the disadvantages and limitations of geothermal energy. • The archaeological sites at Pompeii and Akatori For each site try to find out: - the volcanic history; - when archaeological work started and how it proceeded, - the significance of discoveries made. • A famous volcanic site either overseas (e.g. Mt Fuji, Old Faithful Geyser, Santorthi) or in Australia (e.g. the Blue Lake, the Classhouse Mountains or Tower Hill) Try to find out - the location of the site; - its volcanic history, - its significance (e.g. tourist destination, scientific research, recreation). Visible signs Rtsung magma is indicaled by bulging of the ground (Figure 2). This is measured using a Iiltmeii~r, Small ash and la’s emksions may also precede a rnajo€ eruption. Gas emissions Eruptions may be pre.ceded by increases in voLcanic gases such as hydro~cru sulphids nnd sulphur dioxide Gas detectors are used to mcasurc these emissions. 4.... Historical records Records of past eruptions çaq give broad indication of the lukelihoud of eruplirms in che Irnure. Such predtctioris arc unlikely to be accur~ie enough to he acted upoit Fl~urc 2: The initial tacerii] blast uf hoi glowing gas on the north Mope olMi Sr Helens. USA. 18 May 1980. Fin li-k and magnetic changes A cnagnomcT~cr irnd electmdes can be used to detect changes in the elecincal and niagructic propetlits of rocks. whEch typically precede an erupuon. Magma movement Small c~&rthq1iakes (measured using a scismumcier) and changes in teinperattite ax the surface both indicate aisir~ magma and ‘he possibility of an ciupuori Figure 1 Vulcanologist repeats warning LEGAZP], Philippines The Government’s chief vu]cartotogist has defended his predictons about Mayon vo]aino and s-aid thousands of refugees should stay itt evacuation centres at leact a week before reiurrnng to theft homes oeai- the slopes The Phi Iipp4nes Insutule of Vulcanology and SeFsmology had warned of a possible major crupuort on Sunday due to gcaviiational ,ntluences qf a lull noon and high tides. No eauption occurred Abouc 42,000 pe~çle fled their homes after s mild eruption ~n February 2 killed 6S people, because of forecasts of another eruptcon. Ipistituce I)irec.tnr Ravmuado Puumngbayan said Forecastb~ aciiviiy at Mayout was difficult because the vok~ano has an open vent, meaning dial insinirn ems cannot accurate~y detect changes in pressurE or ruoVertiertt of magma Officials SaLCI there were no epidemics among rcrug~s. most of them impoverished farmeis, But hcatih officials said about 400 people were sulfeting from acerne respiratory infEctions due to sulphur and ash irthakition, Source- Cwthernz Tatter. Ftbrxcan JO, J9~3 Figure 3 106 Predicting Volcanoes Possibilities for predicting Activities volcanic eruptions 1 Using the information in }~igue 1~ arid additional research if necessary: a Describe each of the following instruments and e~xptain their funci-tort in the predictkirt oL vokaaic actk’ity: ‘ seisrnogr~ph • tiitmeter • m~gnometer * gas detector Ii Explain the hmnations of using historical records in the prediction of volcanic activity? What other uses could be made of such records to help reduce the impad of ~i major eniption? 2 a En April 1980. a bulge appeared on the side of Mt St Helens, USA- The bulge grew at a tate of ab.t-iut 2 metres a day until the May 1.8 enip Lion 3hnwrl ift Figure 2. What wa~ the probable cause ni the hutge7 The bulge was high on (he north slope of the mountain. Whal happened L-O it when the volcano erupted’ b Conduct some research into the Mt St Hdens eruption. Focus on attempts by scientists to predict when the volcano would occur. Evatuate the success of their predictions, in terms of rediicing the impact of the eruption. 3 Using the nformaIio~ in Figure 3 to help you1 explain some of the dii! kultics ass nt-ia ted with predicting volcanic activity. Section 8 Volcanoes 107 Repo fling Disasters: Rabaul Volcanic Eruptions, 1994 Looting gangs raid volcano town from RORY CALLIINIIAN VUNAPOPE, New Britain: Riot police wilt move into Rabaul today to stop armed gangs looting what is left of the town devastated by volcanic eruptions. Gangs of criminals, known as ras cals, arc roaming the provincial cap ital of the Papua New Guinea island of New Britain, pillaging shops and houses, stealing cars and robbing re maining residents. A squad of 20 riot police was air lifted into nearby Tokua yesterday. Australian expatriate Ms Tanya Bereny said gangs were ‘running around’ Rabaul, armed with knives and wearing balaclavas. She and a group of locals had driv en out of the hotel to Vuapope, a vil lage south-east of Rabaul, late on Tuesday. ‘We ran into roadblocks manned by people with knives who threat ened to take our vehicle’ Ms Bereny said. ‘We didn’t think we would make it.’ As the last surviving residents were snatched from beneath clouds raining scorching sulphur yesterday, a lone Australian trapped for two days under the sagging roof of his home waded to safety - and pro nounced the town officially dead. ‘Rabaul is destroyed, it’s gone, it’s finished. It just doesn’t exist any more,’ engineer Mr Michael Jasny told his wife and family in a phone call to their Townsville home. And dramatic pictures of a dust- covered wasteland confirmed Rabaul was not just dead, but buried Meanwhile, emergency aid centres around the Rabaul district were being swamped by refugees seeking food and shelter. More than 45,000 people have Figure 1 been evacuated from Rabaul to near by villages since the volcanoes - Vul can and Tavurvur - began erupting on Monday. The survival of Mr Jasny, a 49 year old Vietnam veteran and aircraft maintenance engineer, was one of the most astonishing stories to emerge from the chaos. He had waited for rescue, terrified and alone, as his house disappeared under a mountain of ash. Speaking from an emergency camp at Kokopo, about 20km from Rabaul, Mr Jasny told how he strug gled knee-deep in ash through the town, leaving his house just as it fi nally crumbled. ~Rabau1 is destroyed, it’s gone, it’s finished. It just doesn’t exist anymore., Australian engineer Michael Jasny Suddenly, through the dust clouds, he saw a four-wheel-drive vehicle. At the wheel was his father-in-law, Mr Hans Van Der Drift, who had gone searching for him after other rescue missions had failed Mr Jasny’s nightmare began early on Monday, when he woke to find the entire town centre deserted. A code 4 alert had been issued while he slept No-one woke him and he was left stranded Until he made phone contact with his family, no-one knew of Mr Jas ny’s plight until Mr Van Der Drift called the Foreign Affairs De partment and told them he was stranded As the dust, ash and mud began to bury his home, Mr Jasny’s only life line was the telephone. Talking to his family from the house as it collapsed around him, Mr Jasny told them that he had ‘better speak now because I could be dead in a couple of hours. A football field in Vunapope has become a makeshift refugee camp crammed with homeless families. Up to 1000 people are camping at the airstrip at Tokua, waiting to catch planes out. Hundreds of others have fled in boats and larger vessels. Helicopter pilot Mr Tony Aldridge said a ‘rain of fire’ sent terrified vil lagers fleeing into the sea. Mr Aldridge, who has been fer rying people and supplies to evacua tion centres, said about 600 people had been caught under a huge cloud of burning ash. ‘They paddled out to sea and clung to barrels to avoid the ash. They were picked up by ship, he said Commercial ships operating near Rahaul yesterday made several dra matic rescue missions, picking up more than 3000 villagers. An Australian RAAF Hercules made two trips to Vunapope yes terday, carrying clothes, water, food. oxygen cylinders, tele communications technicians and a generator for the Vunapope hos pital, which has also become a major evacuee centre. On the return flight to Port Mores- by, the plane carried critically ill pa tients from local hospitals. Meteorologists are monitoring the path of the massive ash cloud as it heads south-west toward the main land of Papua New Guinea. Airlines have been warned, and Qantas has diverted a ‘handful’ of flights to Japan to avoid the danger ous ash particles, which cause engine failure in jets. Source. The Advertiser, September 22, 1994 Reporting on Disasters: Some common features Disasters are given major coverage Stories about disasters are often prominent in news papers and on television and radio. The media are able to provide information, graphic film and pictures, expert opinion and eyewitness accounts very soon after the event has occurred Local events are preferred Disasters which happen in Australia. even if they are not significant, are often given preferred coverage over those which happen overseas. This is particularly the case if the overseas event is in a developing country or a country with which Australians are not familiar Disasters are oversimplified The complex nature of a disaster is rarely conveyed through media reports Ambiguous information is removed so that the story is easy to follow This is commonly done by highlighting the spectacular survival (or terrible plight) of one, or a few, people Sensational aspects are highlighted Gruesome death, spectacular escape and heroic rescue are common features of disaster stories. These are often highlighted at the expense of important information about the cause, duration and effects of the disaster, and people’s efforts to minimise its impacts. Section 8 Volcanoes ins Reporting Disasters: Rabaul Volcanic Eruptions, 1994 (contd) Figure 2 Activities 1 Read Figure 1. ‘Looting gangs raid volcano town’, on the previous page, and then answer the following: a Which of the features of disaster reporting shown in Figure 2 are represented in the story7 To support your answer, underline or highlight sections of the story which show each of these features. b Comment on the headline of the story. Why do you think it was chosen? Is it a good indication of the information which is contained in the article? c Why do you think a large part of the story is devoted to Mr Jasny’s experiences during and after the volcano? d What is the function of the large text highlight in the centre of the article? Comment on the ability of the person quoted to make such a claim, and therefore, its likely accuracy. e Choose at lçast two examples of sentences or phrases used to describe the volcanic eruptions and their aftermath. Comment on (i) the language used in the descriptions and (ii) the amount of information they provide about the disaster. f Why do you think this disaster was given far greater prominence in the Australian media than in the media in the USA, Britain and Europe2 g Disaster reporting has been desenbed as ‘infotainment’ rather than news What do you think is meant by this? Would you describe Figure 1 as ‘infotainment’ or ‘news’? Explain your answer. 2 Study the information in Figure 2 and answer the following: a Why do you think a disaster such as a major volcamc eruption is lilcely to receive more media coverage than a less spectacular event such as a drought? b In reporting disasters, what advantages do newspapers, television and radio have over other information sources such as books and magazines? c In 1989, the Armenian earthquake which killed 25,000 people, was pushed off of the front pages of the English newspapers by a rail crash in London. Why do you think the decision was made to give the local event greater prominence? Why would aid agencies trying to raise money for relief work in Annenia have been particularly concerned by this decision? 3 Conduct some research of your own into the reporting of disasters in the media. The following steps can be used as a guide: (i) Collect a series of newspaper articles or video segments which report on disastrous events. (ii) Analyse your collection in terms of the features listed in Figure 2. e.g. • Which features are most prominent? • What are some of the examples of reporting according to each of these features7 • Which features are not represented? • Can you suggest additional features of disaster reporting not listed in Figure 2’ (iii) Comment on other characteristics of your collection: e.g. headlines, film/photographs used and length, timing and prominence of the items reported. An Introduction to Hazards and Disasters Page 21 Word Puzzle: Bushfires The sentence down the centre of the puzzle is therefore. Will I stay or evacuate? ~Section3 The Flood Hazard Page 31 The destructive effects offloods 109 111 Self Check Answers answers Section 1 Section 2 The Bushflre Hazard Pages 6, 7 Find-a-word: Hazards and Disasters 1 Avalanche 2 Famine 3 Subsidence 4 Army S Smog 6 Earthquake 7 Heatwave 8 Plague 9 Hobart 10 Volcano 11 Soil Erosion 12 Tracy 13 Tornado 14 Oil Spills 15 Hurricane 16 Flood 17 SES 18 Ozone 19 Murray 20 Drought 21 Rescue 22 Pollution 23 Bushfire 24 Tsunami 25 Acid Rain 26 Eyre 27 Tropical cyclone 28 Nuclear 29 Landslide 30 Rabbits 31 Mali 32 Newcastle 33 EMA 34 Cane 35 Japan 36 Hailstorms 37 Locusts 38 Shock 39 Faults 40 Algae 41 Salinity 42 Dust 43 Flash 44 Brisbane 45 Seismograph 46 Dams 47 Bangladesh 48 Richter 49 Vesuvius SO Levee 51 Typhoon 52 Severe 53 Monsoon 54 Lava 55 Surge 56 Forest 57 Bombing 58 Low 59 Spot 60 Ash 61 Salt 62 Dome 63 Cone 64 Magma 65 Eucalypts 66 Vent The remaining letters make up the word. Predicfion I North winds 2 Humidity 3 Woollen 4 Eucalypts 5 Uphill 6 Livestock 7 Victoria 8 Retardent 9 Dehydrate 10 Controlled 1 Drowning 2 Oil Mud 3 Currents Turbulent 4 Debris 5 Foundations Weak Mortar Earth 6 Sewerage Water Disease 11 Firebreaks 12 Forests 13 Television 14 Inhalation 15 Protection 16 Precautions 17 Tasmania 18 Ignition 19 Wednesday 7 Saturation Landslides 8 Floodplains 9 Power 10 Penned Crops 11 Depth 12 Cultural 13 Fishing The remaining letters form the word Coastal Self Check Answers (contd) The Flood Hazard (contd) Page 35 Controlling Floods (Activity 4) Section 4 The Severe Storm Hazard Page 43 What are Severe Storms? The words down the centre of the puzzle are therefore: Thames Barrier The Tropical Cyclone Hazard Page 56 Tropical Cyclones Explained (Activity 4) The name down the centre of the puzzle is therefore: 110 rvi I Education 2 Flash flood 3 Evacuation 4 River Murray 5 Protection 6 Storm Surges 7 Levee banks 8 Forecasting 9 Insurance 10 Barrages 11 Brisbane 12 Diversion 13 Saturation 1 Land 2 Lightning 3 Cyclones Earthquakes Floods Bushfires 4 Area 5 Frequently Hazard 6 Costs 7 Debris 8 Boats 9 Trees 10 Flash Rain 11 Hail 12 Tomadoes Deaths 13 Force 14 Thunder Page 40 Crossword: Floods Across 1 Diversion 6 Tsunami 7 Evacuation 12 Levees 13 Murray 14 Bangladesh 16 Nile 17 Aid 19 New South Wales 22 Cities 23 Roads 25 Barrier 26 Erosion 27 Proofing Down 2 Silt 3 Waterlogged 4 Catchment 5 Forests 8 Floodplain 9 Brisbane 10 Flash 11 Eyre 15 Mississippi 18 Runoff 20 Sediment 21 Storm 24 Dams 1 Tropics 2 Isobars 3 Hurricane 4 Direction 5 Typhoon 6 Depression 7 Predict 8 Circulate 9 Eyewall 10 Queensland 11 Cloud cover Port Hedland Page 62 Storm Surges 1 Tropical 2 Sea Low Buildings 3 Bays Headlands Islands 4 Intensity Speed 5 Drowning 6 Normal 7 Angle Shape 8 Dome Tide 9 Wave 10 Winds Coastal 11 Slope The Tropical Cyclone Hazard (contd) Page 66 Crossword: Tropical Cyclones Page 82 Crossword: Drought Section 6 The Drought Hazard Page 81 Drought and Farm Management (Activity 4) Section 7 The Earthquake Hazard Page 96 Crossword: Earthquakes The words down the centre of the puzzle are therefore: Con tour Banks 111 Ill Self Check Answers (contd) Across 6 Typhoon 8 Anemometer 9 Low 10 Anticyclone 13 Storm Surge 17 Queensland 18 Bengal 21 Florida 22 Floods 23 Iron 24 Hedland 25 Fiji 26 Tropics Down I Gale 2 Darwin 3 Isobars 4 Beaufort 5 Knots 7 Hurricane 11 Cumulonimbus 12 Eye 14 Tracy 15 Radar 16 Meteorology 19 Tornadoes 20 Satellite Across 1 Food 3 Sudan 4 Aid 5 Pollution 7 Prices 9 Desertification 11 Sheep 12 Farmers 16 Dry 17 Diseases 21 Pasture 24 Industry 26 Water 27 Bushfires 28 Queensland Down 1 Famine 2 Dams 3 Snow 6 Income 8 High 9 Duststorms 10 Fertility 13 Australia 14 Ash 15 Watertable 18 Crops 19 Rains 22 Topsoil 23 Adapted 25 Arid 1 Fencing 2 Pest control 3 Retention 4 Agistment 5 Ground 6 Pollution 7 Degraded 8 Windbreaks 9 Native 10 Lucerne 11 Stocking 12 Erosion Across 5 San Andreas 6 Epicentre 7 Seismograph 10 Eurasian 11 Richter 14 Magnitude 17 Newcastle 19 Collapse 21 Focus 22 Fire 23 Cities 24 Shock Down 1 Water 2 Mantle 3 Sea 4 Japan 8 Plates 9 Prediction 12 Crust 13 Tsunami 14 Meckering 15 Tremors 16 Subsidence 18 Faulting 20 Mexico 112 111 t1tbhhhh1~t.1 Self Check Answers (contd) Section 8 The Volcano Hazard Page 100 What is a Volcano? (Activity 3) Clues 1 Magma 2 Crater 3 Eruption 4 Secondary 5 Vent 6 Chamber 7 Composite 8 Cinders 9 Shield 10 Lapilli 11 Bombs 12 Common 13 Ash 14 Convex 15 Layers 16 Cone 17 Lava 18 Dome The remaining letters form the word: Tephra Page 102 The Destructive Effects of Volcanoes I Tsunamis 2 Forests Roads Crops 3 Landslides Mudflows 4 Slope Floods 5 Lava Ash 6 Evacuation 7 Active 8 Earthquakes 9 Death Low 10 Whole 11 Wind 12 Population Close 13 Food Shelter 14 Resettled 15 Rivers 16 Coast 17 Time The remaining letters form the word: Eruption