1、Watchthevideotoknowabouttsunami.Totalkaboutthesafetyinstructionsabouttsunami.Discussonthereliefworkaftertsunami.Video TimeVideo Time2LeadinWhatnaturaldisasterdoesthepicturesshow?tsunamiLeadinTsunami:KillerWaveTsunami waves can strike out of nowhere and cause a lot of destruction.Scientists study and
2、 track tsunamis in order to warn people and minimize deaths.不知从哪里不知从哪里v.跟踪，追踪跟踪，追踪v.降低，减少降低，减少Work in groups.Discuss the following questions.Warmingup1.What is tsunami?2.What causes a tsunami?3.What should we do when a tsunami hits?4.Do you know some safety instructions?Warmingup1.What is tsunami?At
3、sunamiisaseriesofoceanwavesthatsendssurges(急剧上升)ofwater,sometimesreachingheightsofover100feet(30.5meters),ontoland.Thesewallsofwatercancausewidespreaddestructionwhentheycrashashore.Warmingup2.What causes a tsunami?Thesewavesarecausedbylarge,underseaearthquakesattectonicplate(地壳板块)boundaries.Whentheo
4、ceanfloorataplateboundaryrisesorfallssuddenly,itdisplacesthewateraboveitandlaunchestherollingwavesthatwillbecomeatsunami.Itmayalsobecausedbyunderwaterlandslidesorvolcaniceruptions.Warmingup3.What should we do when a tsunami hits?4.Do you know some safety instructions?Ifyouheartsunamiwarning,evacuate
5、atonce.Goashighandasfarasyoucanatleasttoaspot30metersabovesealevel(海平面)or2milesaway.Takeyouremergencykit.Drop,cover,andholdontoprotectyourselffromthepossibleearthquake.Avoiddownedpowerlinesandstayawayfrombuildingsandbridgesfromwhichheavyobjectsmightfallduringanaftershock(余震).BeforeyouwatchReadthesen
6、tencesabouttheformation(组成)andeffectsoftsunamis.Thenmatcheachsentencewiththecorrectpicture.A.Tectonicplatespushtogether.B.Aseriesofwavesexpandsinalldirections.C.Wholesectionsofcitiesaredestroyed.ACB地壳板地壳板块v.延展，延展，延申延申朝四面八方朝四面八方n.部分部分WhileyouwatchDecidewhetherthestatementsaretrue(T)orfalse(F).1.There
7、arefewwarningsignsjustbeforeatsunamihits.2.Atsunamibreaksjustlikeanordinarywavebutisbigger.3.ScientistsatthePacificTsunamiWarningCentermonitortheearthsmovements24hoursadayinordertotracktsunami.Atsunamiwavedoesntbreaklikeanordinarywave.TFTWhileyouwatchCirclethecorrectword(s)ineachsentence.1.An earthq
8、uake occurs when plates below the earths surface pushtogether/pullapart.2.Tsunami waves deep at sea move fast and rise onlyafew/hundredsoffeet.3.As these killer waves enter shallow waters,their speed is reduced/raised.4.Most tsunami damage is caused when the waves comeinfrom/movebackouttothe sea.v.s
9、trike,hit,happenadj.浅的浅的AfteryouwatchWorkinpairs.Discussthequestions.1.Whathaveyoulearntabouttsunamis?2.Whatkindofhelpdoyouthinkpeoplewhohavesufferedfromatsunamineed?AfteryouwatchWorkinpairs.Discussthequestions.1.Whathaveyoulearntabouttsunamis?Theyarentnoticeableorstronguntiltheyhitthecoast.dangerou
10、sdestructivedeadlydisastroussuddenAfteryouwatchWorkinpairs.Discussthequestions.2.Whatkindofhelpdoyouthinkpeoplewhohavesufferedfromatsunamineed?Theyneedfood,water,shelter,etc.Theymayalsoneedmedicalhelpandemotionalhelpiftheyhavelostlovedones.Lets watch another video about tsunami.Finish 步步高（P71-P74)17
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