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

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