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1、8Composergermson红色为重点蓝色为次要黑色为最次，但三篇都要求会背+第十五篇“Liquefaction”KeytoMuchofJapaneseEarthquakeDamageThemassivesubductionzone1earthquakeinJapancausedasignificantlevelofsoil"liquefaction"2thathassurprisedresearcherswithits1severity,anewanalysisshows."We'veseenlocalized3examplesofsoil
2、liquefactionasextremeasthisbefore,butthedistanceand2ofdamageinJapanwereunusuallysevere,"saidScottAshford,aprofessorofgeotechnicalengineering4atOregonStateUniversity5."Entirestructuresweretiltedandsinkingintothesediments,"Ashfordsaid."Theshiftsinsoildestroyedwater,drainandgasp
3、ipelines6,cripplingtheutilitiesandinfrastructurethesecommunitiesneedto3.Wesawsomeplacesthatsankasmuchasfourfeet."Somedegreeofsoilliquefaction7iscommoninalmostanymajorearthquake.It'saphenomenoninwhichsoilssoakedwithwater,particularlyrecentsedimentsorsand,canlosemuchoftheir4and
4、flowduringanearthquake.Thiscanallowstructurestoshiftorsinkor5.Butmostearthquakesaremuch6thantherecenteventinJapan,Ashfordsaid.ThelengthoftheJapaneseearthquake,asmuchasfiveminutes,mayforceresearcherstoreconsidertheextentofliquefactiondamagepossiblyoccurringinsituationssuchasth
5、is8."Withsuchalong-lastingearthquake,wesaw7structuresthatmighthavebeenokayafter30secondsjustcontinuedtosinkandtiltastheshakingcontinuedforseveralmoreminutes,"hesaid."Anditwasclearthatyoungersediments,andespeciallyareasbuilton8filledground,aremuchmorevulnerable."Thedataprovide
6、dbyanalyzingtheJapaneseearthquake,researcherssaid,shouldmakeitpossibletoimprovetheunderstandingofthissoil9andbetterprepareforitinthefuture.Ashfordsaiditwascriticalfortheteamtocollecttheinformationquickly,10damagewasremovedintherecoveryefforts9."There'snodoubtthatwe'lllearnthi
7、ngsfromwhathappenedinJapan10that11willhelpustoreducerisksinothersimilar11,"Ashfordsaid."Futureconstructioninsomeplacesmaymakemoreuseoftechniquesknowntoreduceliquefaction,suchasbettercompactiontomakesoilsdense,oruseofreinforcingstonecolumns."AshfordpointedoutthatnorthernCalifo
8、rniahaveyoungersoilsvulnerabletoliquefaction---onthecoast,nearriverd
