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BeforeWatching
ProgramovervieW
NOVAexploreswhathappenedandwhywhentheDecember26,2004,tsunamidevelopedofftheSumatrancoast.
Theprogram: •trackstheIndianOceantsunamiasit
progressesoutwardfromitsepicenter. •noteshowEarth’scontinentalplatescancreateearthquakes
whentheycollide. •describeshowthetsunamidevelopedfromanearthquakethat
occurredatasubductionzoneofftheSumatrancoast. •relateshowthePacificTsunamiWarningCenterinHawaiifirst
registeredtheearthquakebut,duetolackofanytsunamisensornetworksinthatregion,wasunabletoknowifatsunamihadformed.
•recountsthroughdescriptionsandanimationshowthetsunamidevelopedaftertheearthquake,howittraveledintheopenocean,andhowitamplifiedasitnearedtheshoreline.
•interviewssurvivorsinseverallocationsandshowsthedestructioncausedbythewaves.
•detailstheinfluenceofcoastalmorphologyandseabedgradientonthetsunami’sdestruction.
•relateshowPacificTsunamiWarningCenterofficialswereeventuallyabletocalculatethetsunami’straveltimeandalertEastAfricanembassiesofitsimpendingarrival.
•recountsotherIndonesiantsunamisandpointsoutthatsomescientistshadpredictedcatastrophicgeologicalactivityinthatregion.
•considerstheimpactthatnotsunamiwarningsystemorlittletsunamieducationhadontheoutcomeofthedisaster.
•reviewsthefourmaincausesoftsunamis—earthquakes,meteorimpacts,volcanicorotherexplosiveeruptions,andabove-waterandundersealandslides.
•statesthatwhile,bysomeestimates,tsunamisposeadirectthreattoaboutone-quarteroftheworld’spopulation,protectionagainstthemremainsamatterofcostandpolitics.
•speculateswhatcouldhappenifamajorearthquakeoccurredattheCascadiasubductionzoneoffthePacificNorthwestcoastoriftheCumbreViejavolcanointheCanaryIslandscollapsedintothesea.
1Discusswithstudentswhatatsunamiisandhowitcanbecreat-ed.Defineepicenter.(SeeActivityAnsweronpage4formoreinfor-mation.)Havestudentsuseanatlastolocatesomeoftheplacesintheprogram—theIndianOcean,Sumatra,Thailand,SriLanka,andEastAfrica.
2Drawachartontheboardthatcomparestsunamisandwind-drivenwaves.(SeeActivityAnsweronpage4formoreinformation.)Discussthemaindifferencesbetweenthesewavetypes.
3Organizetheclassintofourteamsandassignatsunamitopictoeachteam:physicalcharacteristics,awarenessandsafetyinformation,occurrenceworldwide,andimpactonlife.Haveteamsgenerateques-tionsrelatedtotheirtopics.Asstu-dentswatch,havethemtakenotesontheirareasoffocus.
1Providetimeforteamstoresearchquestionstheywrotedownthatwerenotansweredintheprogram.Haveteamssharewhattheylearned.Whatfindingssurprisedstudentsthemost?
2Askstudentstoconsiderwhytsuna-miscansometimescausesuchdamageanddevastation.Whataresomecharacteristicsofthewavethatfactorintohowmuchdamageitcouldcause?(Somecharacteris-ticsincludesizeandspeed.)Howdocoastalorshorelinefeaturesfac-torintotheextentofdamage?(Cliffscanbuffersomeoftheenergyandlimitdamage;openshorelineswithgradualinclinescanresultinmoresubstantialdamage.)Whatrolecouldawarningsystemplay?(Awarningsystemcouldpotentiallyhelpsavelives.)
afterWatching
�
WaveThatShooktheWorld
novateacher’sguidewww.pbs.org/nova/tsunami
tapingrights:Canbeuseduptooneyearaftertheprogramistapedofftheair.
originalbroadcast:march29,2005
cLassroomactivitY
objectiveTocalculateapproximatespeedsandtraveltimesforsampletsunamis.
materialsforeachteam•copyof“TrackingTsunamis”studenthandout•copyofthe“TsunamiScenarios”studenthandout•copyofthe“WorldMap”studenthandout•calculatorwithsquarerootfunction•drawingcompass•ruler
materialsfortheclass•worldatlases
Procedure1 Reviewsubductionzonesandhowearthquakesoccurinthesezones.
(SeeActivityAnsweronpage4formoreinformation.)Drawasub-ductionzoneontheboardandreviewwithstudentshowtheDecember26,2004,earthquakeoffoftheSumatrancoastcreatedatsunami:Amassivedisplacementofwaterfromitsequilibriumpositioncausedthetsunami.Gravityworkedtorestorethewatertoitsequilibriumposition.Thewavestraveledfromtheirplaceoforigininalldirectionsandenergyfromthequakewastransferredbythewater.
2 Tsunamis,becauseoftheirlongwavelengths,loselittleenergyastheytravel.(Therateatwhichawavelosesenergyisinverselyproportionaltoitswavelength.)Informstudentsthatthereisaformulathatcanbeusedtoestimatethespeedofthewavecreatedfromthisenergy.Theformulaisusedtomeasurethespeedofoceanwaves,liketsunamis,thathaveverylongwavelengthsrelativetothedepthofthewater.Tsunamiscanhavewavelengthsgreaterthan700kilometers(theaverageoceandepthis3–4kilometers).Theformulaestimatesthetsunami’sspeedwhileitisindeeperwaters(asitapproachesshallowercoastalwaters,thetsunamislowsdown,itswavelengthshortens,anditsheightincreases).
� novateacher’sguidewww.pbs.org/nova/tsunami
WavethatshooktheWorLd
The“TrackingTsunamis”activityalignswiththefollowingNationalScienceEducationStandardsandPrinciplesandStandardsforSchoolMathematics.
GRADES 5–8ScienceStandardB:PhysicalscienceTransferofenergy•Energyisapropertyofmany substancesandisassociatedwith heat,light,electricity,mechanical motion,sound,nuclei,andthe natureofachemical.Energyis transferredinmanyways.
ScienceStandardD:earthandspacescienceStructureoftheEarthsystem•Lithosphericplatesonthescalesof continentsandoceansconstantly moveatratesofcentimetersper yearinresponsetomovements inthemantle.Majorgeological events,suchasearthquakes, volcaniceruptions,andmountain building,resultfromtheseplate motions.
mathematicsstandard:NumberandOperations
standardsconnection
Video is not required for this activity.
classroomactivityauthor
DevelopedbyWGBHEducationalOutreachstaff.
cLassroomactivitY standardsconnection (cont.)
3 Brainstormwithstudentssomefactorsthatmayplayaroleinthespeedofatsunami.(Studentresponsesmayincludethemagnitudeofanearthquake,theamountofdisplacedwater,andthedepthofthewater.)Tellstudentsthattheformulatoapproximatetsunamispeedconsidersthedepthofthewaterandtheaccelerationduetogravity.Theformulais:
wherespeed(meters/second)=squarerootofg(accelerationduetogravity,whichis9.81meters/second2)xd(waterdepthinmeters)
4 Havestudentsworkwithapartner.Provideeachteamwithacopyofthehandoutsandothermaterials.Reviewthehandoutswiththem.Tellstudentsthattheywillusethespeedformulatocalculatetsunamispeedanddeterminethetimeeachtsunamitakestotraveltospecificlocationsineachofthescenariospresented.Studentscanchecktheirdistanceestimatesatwww.wcrl.ars.usda.gov/cec/java/lat-long.htm
5 Studentswillneedtoconverttheiranswers,whichwillbeinmeters/second,tokilometers/hour.Helpstudentsthinkhowtheymightmovethedecimalpointtoaccomplishthelaststepinthisconversion.
6 Toconclude,holdaclassdiscussionabouttheorderinwhichthetsunamiwillstrikeeachlocation(1st,2nd,or3rd).Haveteamssharesomewayspeopleateachlocationmightpreparefortheapproachingtsunami.(Someconsiderationsareevacuatingpeopletohighground,alertinghospitals,decidingwhetherthereistimeforhelpfromoutsidethecountry,orsendingpeopleawaybyboat.)
7 Asanextension,askstudentstoresearchwhyandhowthePacificTsunamiWarningCenterwasdevelopedandwhatfutureplansarebeingformulatedforaworldwidetsunamiwarningsystem.
WavethatshooktheWorLd �
GRADES9–12ScienceStandardB:PhysicalscienceMotionsandforces•Gravitationisauniversalforcethat eachmassexertsonanyother mass.Thestrengthofthe gravitationalattractiveforcebetween twomassesisproportionaltothe massesandinverselyproportional tothesquareofthedistance betweenthem.
Conservationofenergyandtheincreaseindisorder•Thetotalenergyoftheuniverseis constant.Energycanbetransferred bycollisionsinchemicalandnuclear reactions,bylightwavesandother radiations,andinmanyotherways. However,itcanneverbedestroyed. Asthesetransfersoccur,thematter involvedbecomessteadilyless ordered.
Interactionsofenergyandmatter•Waves,includingsoundand seismicwaves,wavesonwater,and lightwaves,haveenergyandcan transferenergywhentheyinteract withmatter.
mathematicsstandard:Algebra
novateacher’sguidewww.pbs.org/nova/tsunami
speed= gxd
activitYansWer
Atsunamiisaseriesofwavescreatedinabodyofwaterbyadisturbancethatverticallydisplacesthewatercolumn.Tsunamisarenottidalwaves(theyarenotcausedbytheforcesthatcreatetides).AnepicenteristhepointonEarth’ssurfacestraightabovewhereanearthquakeoriginates.
Waterwavesaregroupedbytheforcesthatcauseorgeneratethem(generatingforces)andthosethatrestoreequilibrium(restoringforces).Thegeneratingforcesaredifferentfortsunamisandwind-drivenwaves,buttherestoringforceforbothisgravity.
Mosttsunamisarecreatedbysub-marineearth-quakesthatoccuratsubductionzones.Atthesezones,onetectonicplateismovingorsubductingbeneathitsneighboringplate.Manythingscanhappenatthesesitestotriggeratsunami.AtSumatra,stick-slipfrictionoccurred.Theupperplatedraggeddownwardwiththelowerplateandthentheupperplatebecamedeformed,builtupstrainenergy,andthensnappedup.Themagnitudeofanearth-quakedetermineshowmuchenergyisreleasedandthentransferredbythewater.Theearthquake’smagnitudealsoplaysaroleinhowhighabovesealevelthewaterlevelrises.Magnitudedoesnotplayalargeroleinthetsunami’sspeed.
Severalfactorsaffecttheheightofatsunamiwaveandthedamageitcancauseasitapproachesandreachestheshore—theenergythewavecarries;thetides,whetherhighorlow;andthelandformationandfeatures.
� novateacher’sguidewww.pbs.org/nova/tsunami
scenarioa TheSeward,Alaska,tsunamicreatedat
anoceandepthof4,000miscalculatedtotravelat713km/h.Thetraveltimestoeachlocationare:kodiak,alaska:about32minutes
kauaiisland,hawaii:about6hours kwajalein,marshallislands:about9hours
26minutes
scenarioB: TheKaLae,Hawaii,tsunamicreatedat
anoceandepthof4,500miscalculatedtotravelat756km/h.Thetraveltimestoeachlocationare:
dutchharbor,alaska:about5hours6minutes kwajalein,marshallislands:about5hours
30minutes samoa:about5hours30minutes
scenarioc: TheGranCanaria,CanaryIslands,tsunami
createdatanoceandepthof3,500miscalculatedtotravelat667km/h.Thetraveltimestoeachlocationare:
terceira,azores:about2hours21minutes safi,morocco:about1hour5minutes st.Johns,newfoundland:about5hours
44minutes
WavethatshooktheWorLd
kindofWave
wind-driven
seismic-seawave(tsunami)
modeofgeneration
localordistantwindsthatblowacrosstheocean’ssurface
sub-marineearthquakes(mosttsunamis);alsocreatedbyvolcaniceruptions,land-slides,underwaterexplosions,andmeteorimpacts
rangeofWavelength
about100mto200m
from100mto>500km;areatleastthreetimestheoceandepthatwhichthewavewasgenerated
Wavefrequency(Period)
5sto20s
10minto2h
Wavespeed
about40to90km/h(40km/h,thespeedofamoped,ismostcommon)
variable,upto1,000km/h(thespeedofajetplane)
MajorfundingforNOVAisprovidedbyGoogleandBP.AdditionalfundingisprovidedbytheHowardHughesMedicalInstitute,theCorporationforPublicBroadcasting,andpublictelevisionviewers.
LinksandBooks
LinksNOVAWebSite—WaveThatShooktheWorldwww.pbs.org/nova/tsunami
In this companion Web site to the program, find out about how well officials can prepare for the next big tsunami, read an Ask the Expert feature, see how the Indonesian event unfolded, and delve into the global history of these seismic sea waves.
CalculatingtheThreatofTsunamiwww.science.org.au/nova/045/045key.
htm
Defines the term tsunami and includes information about wave energy.
EarthquakesandSocietywww.umich.edu/~gs265/society/
earthquakes.htm
Includes charts and information about earthquakes at subduction zones.
TheGreatSumatraEarthquakeandTsunamiofDecember2004www.wilson.wnyric.org/t/drobison/
regents/Wellorganized/tsunami.htm
Provides a five-part high-school level earth science lesson plan that explores the geologic processes involved with the Indonesian tsunami. Includes analysis of actual seismograms from which stu-dents plot the earthquake’s epicenter.
HyperPhysics:Tsunamihyperphysics.phy-astr.gsu.edu/hbase/
waves/tsunami.html
Includes graphics of subduction zones and describes how tsunamis travel.
InternationalTsunamiInformationCenterwww.prh.noaa.gov/itic/library/about_tsu/
faqs.html
Answers frequently asked questions about tsunamis and lists the largest historical tsunamis.
LifeofaTsunamiwalrus.wr.usgs.gov/tsunami/basics.html
Explains tsunami speed and amplification.
Oceanography:Waveswww.poemsinc.org/oceano/waves.htm
Contains a map of locations for 13 tsunamis.
PhysicsofTsunamiswcatwc.arh.noaa.gov/physics.htm
Characterizes tsunamis and considers how they travel in different water depths.
Tsunamiwww.tulane.edu/~sanelson/geol204/
tsunami.htm
Describes the physical characteristics of tsunamis and includes definitions of wavelength, wave height, wave amplitude, wave frequency, and wave velocity. Includes formulas for calculating velocity.
Tsunami:FrequentlyAskedQuestionswww.pmel.noaa.gov/tsunami_faqs.htm
Answers questions about causes of tsunamis and how they differ from other waves.
Tsunami—SeismicSeaWavevulcan.wr.usgs.gov/glossary/tsunami/
description_tsunami.html
Describes seismic sea waves and discusses four damaging tsunamis.
U.S.SearchandRescueTaskForce:Tsunamiswww.ussartf.org/tsunamis.htm
Provides basic information about tsunamis, features 10 destructive tsunamis, and presents tsunami safety rules.
WaterWaveselectron4.phys.utk.edu/141/dec8/
december%208.htm
Distinguishes between deep-water waves and shallow-water waves and provides an example of a tsunami velocity calculation.
WhatisaWave?www.gmi.edu/~drussell/demos/
waves-intro/waves-intro.html
Defines a wave and illustrates examples of different waves.
WorldAtlas.comworldatlas.com/aatlas/imageg.htm
Maps latitude and longitude for cities, towns, and villages.
BooksFord,BrentA.andSeanP.Smith.Physicaloceanography.Arlington,VA:NSTAPress,2000.Includes background information, lessons, and activities related to water, waves, and the ocean.
Macquitty,MirandaandFrankGreenaway.eyewitness:ocean.NewYork,NY:DKPublishing,Inc.,1995.Focuses on Earth’s ocean environments and includes a section on waves and weather.
VanRose,Susanna.eyewitness:earth.NewYork,NY:DKPublishing,Inc.,1994.Discusses Earth and highlights modern oceanography, plate tectonics, and the formation of the ocean floor.
WavethatshooktheWorLd � novateacher’sguidewww.pbs.org/nova/tsunami
WaveThatShooktheWorldstudenthandout
TrackingTsunamis
OnDecember26,2004,scientistsatthePacificTsunamiWarningCenterlearnedofthespeedoftheIndonesiantsunamiandtrackeditasitmovedacrosstheIndianOcean.TheywereabletonotifyEastAfricanofficialsoftheimpendingdisaster.Inthisactivity,youwillcalculatetheapproximatespeedofthreetsunamisandcreateatimetravelmapandchartthatshowstheirarrivalatspecificgeographiclocations.
Procedure1 Researchandlabelyourworldmapwitheach
ofthegeographiclocationspresentedinthescenarios.
2 Useyourdrawingcompasstodrawthewavefrontateachlocationasitradiatesoutfromitsepicenter.Placethecompasstipontheepicenterandthepencilonthelandfalllocation,thenmakethelargestarcpossibleonthemap.Dothisforallscenariolocations.
3 Readeachofthescenariosonyour“TsunamiScenarios”handoutandapplytheformulastodeterminetheapproximatespeedofthetsunamiandthetimeittakesforittoreacheachlocation.
4 Foreachscenario,writedowntheorderinwhichthetsunamiwillstrikeeachlocation.Listsomewaysthatpeople,ifnotified,mightpreparefortheapproachingtsunami.
WavesPeedformuLa
wherespeed(meters/second)=squarerootofg(accelerationduetogravity,whichis9.81meters/second2)xd(waterdepthinmeters)
Yourspeedcalculationinitiallywillbeinmeters/second.Convertmeters/secondtokilometers/hourusingthefollowingformulas:1hour=60minutes=3,600seconds1kilometer=1,000meters
Toconvertyourunitstometers/hour,multiplyyourinitialanswerby3,600.Dividetheresultby1,000toconvertfrommeters/hourtokilometers/hour.Roundyourfinalanswertothenearestwholenumber.
traveLtimescaLcuLation
Calculatetraveltimesbydividingdistancebytsunamispeed.Remembertoconvertthedecimalpartofthenumbertominutesbymultiplyingthedecimalpartby60.Forexample,onepointfour(1.4)hoursequals1hourand24minutes.
speed= gxd
WaveThatShooktheWorldstudenthandout
TsunamiScenarios
scenarioa
Seismologistshavejustregisteredanearth-
quakeinSeward,Alaska,thatisbigenoughto
produceatsunami.Theoceandepthis4,000
meters.Usethewavespeedformulatoapprox-
imatethetsunami’sspeed.Aftercalculating
thespeed,useyouratlastoestimatedistances
fromthetsunami’sepicentertoeachlocation.
Calculatethetraveltimetoeachlocationand
writeitonyourmap.
•Kodiak,Alaska
•KauaiIsland,Hawaii
•Kwajalein,MarshallIslands
scenarioc
AlargepartofavolcanointheGranCanaria,
CanaryIslands,hasjustfallenintotheocean
thatis3,500metersdeep.Usethewavespeed
formulatoapproximatethetsunami’sspeed.
Aftercalculatingthespeed,useyouratlasto
estimatedistancesfromthetsunami’sepicen-
tertoeachlocation.Calculatethetraveltimeto
eachlocationandwriteitonyourmap.
•Terceira,Azores
•Safi,Morocco
•St.Johns,Newfoundland
scenarioB
AtsunamihasjustbeendetectedoffofKaLae,Hawaii.Theoceandepthis4,500meters.Usethewavespeedformulatoapproximatethetsunami’sspeed.Aftercalculatingthespeed,useyouratlastoestimatedistancesfromthetsunami’sepicentertoeachlocation.Calculatethetraveltimetoeachlocationandwriteitonyourmap. •DutchHarbor,Alaska •Kwajalein,MarshallIslands •Samoa
WaveThatShooktheWorldstudenthandout
WorldMapLo
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