简介：Itiswellknownthattherearesometorsionaldamagesinearthquakes.InTaibaipark,Jiangyoucity,Sichuanprovince,mostofthestonestatues,whichwereplaceduponthebanistersofonezigzagbridge,exhibiteddifferenttorsionalphenomenain2008Wenchuanearthquake.Thispaperintroducesthetorsionalphenomenaofallthestatuesonthezigzagbridgefirstly.Thenoneeccentricitymodelisestablishedandtheequivalentrotationalaccelerationsarecalculatedinordertoanalyzethecausesofthetorsionaldamage.Inaddition,thetorsionalcomponentsaresynthesizedbyusingtranslationaccelerationsrecordedatJiangyoustationintheWenchuanearthquake.Theresultsshowthattheequivalentrotationalaccelerationislargerthanthesynthesizedrotationalcomponents,whichsuggeststhatthetorsionalphenomenaofthestatuesonthezigzagbridgemightmainlycomefromitseccentricity.ThecomparisonbetweentheestimatedtorsionalcomponentatJiangyouandthatpresentedbyTrifunacshowsthattheyareinthesameorder.Theresearchim-pliesthatthetorsionalphenomenainearthquakesareverycomplicated,andnotonlycausedbytorsionalmotions.

简介：ThispaperpresentsacomparisonbetweentheChineseCodeGB50011-2001andtheInternationalStandardISO3010:2001(E),emphasizingthesimilaritiesanddifferencesrelatedtodesignrequirements,seismicactionsandanalyticalapproaches.Similaritiesinclude:earthquakereturnperiod,conceptualdesign,siteclassification,structuralstrengthandductilityrequirements,deformationlimits,responsespectra,seismicanalysisprocedures,isolationandenergydissipation,andnonstructuralelements.Differencesexistinthefollowingareas:seismiclevels,earthquakeloading,modedampingfactorsandstructuralcontrol.

简介：许多高速公路桥严重地在2008Wenchuan地震期间被损坏或完全崩溃了。领域调查在强烈影响的区域被执行，超过320座桥被检验。一些代表性的高速公路桥的损坏简短被描述，损坏的可能的原因的初步的分析在这篇论文被介绍。最普通的损坏包括了墩列的砍曲折的失败，扩大关节失败，砍关键失败，并且girder由于在girder和轴承之间的弱连接在横过或纵的方向滑动。从这地震接受的教训被描述并且与弄弯并且扭曲的桥的设计有关的建议，轴承和设备的设计被介绍阻止桥墩的girder倒塌，和韧性。为未来的建议为桥在的地震设计和翻新的技术对严重地震区域中等也被建议。

简介：

简介：介绍了2008年10月6日西藏当雄6．6级地震的基本情况，认为当雄6．6级地震势必对西藏的中部及东南部地区的地震活动产生一定的影响，对此次地震提出一些相关问题并进行了分析。

简介：Inanefforttosharethelessonslearnedandtoprovideareferencepointforfutureresearchandengineering

简介：~~

简介：ThesourceparametersoftheYingjiangearthquakesequencesin2008areobtainedbyapplyingspectralanalysisandBrunessourcemodel,basedonthedigitalwaveformdatarecordedbytheYunnanDigitalSeismicNetwork.Thecorrelationcoefficientsarecalculatedusingthelow-frequencyspectralamplitudesof2eventsrecordedbyasamestation,then,eventswithsimilarfocalmechanismaregroupedusingtheclusteringanalysismethod.Comparedtotheobtainedfocalmechanisms,itisfoundthattherearegoodcorrelationswiththeazimuthofPaxesineachclusteringgroup,andthelargerthecorrelationcoefficient,theclosertheazimuthsofPaxes.WedividetheYingjiangareainto3regionstoanalyzethestresslevelandstressdirectionbycombiningthesourceparametersandthemeanfocalmechanismofeachgroup.Theresultsshow:Thechangeandtransformationofthefocalmechanismtypesatdifferentstagescanrepresentthetemporalcharacteristicsoftheregionalstressfield.Iftheearthquakefocalmechanismtypesareconcentratedinatimeperiodandswitchtothedirectionofregionalstressfield,itmaybeasignofstrongearthquake.Thereissomerelationshipbetweenthestressdropandthetypeoffocalmechanism.Thoseearthquakeswithstressfieldsrevealedbyfocalmechanismtypesclosertotheregionaltectonicstressfieldwillhavehigherstressdrop,whilethosewiththefocalmechanism-revealedstressfieldsdifferingalotfromtheregionaltectonicstressfieldwillgenerallyhavealowerstressdrop.

简介：M_s6.8地震在Xinjiang.Themacroseismic在Wuqia区域发生在10月5,2008日震中位于Kyrghyz共和国的Nula村庄，在Xinjiang.The震中紧张的WuqiaYierkeshitan港口的7km西南是度(外面的边阶)紧张的.The区域并且是7354km2和1031km2，respectively.This地震事件在earthquake.stricken区域与趋势NEKzikeaerkate差错belt.Buildings的运动被联系被损坏或影响到某个exte

简介：ThepaperdiscussesquantitativelytheinfluenceoftheYutianMS7.4earthquakeofMarch21,2008andWuqiaMS6.9earthquakeofOctober5,2008onregionalseismicityinXinjiang,andexplainsprimarilythepossiblereasonofearthquakeactivityfeatureinXinjiangaftertheYutianMS7.4earthquakebyanalyzingthestaticCoulombfailurestresschangeproducedbytheYutianMS7.4earthquakeandWuqiaMS6.9earthquake,andtheseismicityfeatureofMS≥3earthquakesinthepositiveCoulombstresschangeregionofKashi-Wuqiajointregion,thecentralsegmentofTianshanMountainandKalpinblock.TheresultshowsthattheYutianMS7.4earthquakeofMarch21,2008,mayencouragetheWuqiaMS6.9earthquakeofOctober5,2008,andtheYutianMS7.4earthquakeandWuqiaMS6.9earthquakemaychangetheseismicitystateinthecentralsegmentofTianshanMountain,KalpinblockandKashi-Wuqiajointregion,andencouragethesubsequentMS≥3earthquakes.

简介：ThispaperreportstheinternalstructuresoftheBeichuanfaultzoneofLongmenshanfaultsystemthatcausedthe2008Wenchuanearthquake,atanoutcropinHongkou,Sichuanprovince,China.PresentworkisapartofcomprehensiveprojectofInstituteofGeology,ChinaEarthquakeAdministration,tryingtounderstanddeformationprocessesinLongmenshanfaultzonesandeventuallytoreproduceWenchuanearthquakebymodelingbasedonmeasuredmechanicalandtransportproperties.Outcropstudiescouldbeintegratedwiththoseperformedonsamplesrecoveredfromfaultzonedrilling,duringtheWenchuanEarthquakeFaultScientificDrilling(WFSD)Project,tounderstandalong-faultanddepthvariationoffaultzoneproperties.Thehangingwallsideofthefaultzoneconsistsofweakly-foliated,clayeyfaultgougeofabout1minwidthandofseveralfaultbrecciazonesof30-40mintotalwidth.Wecouldnotfindanypseudotachyliteatthisoutcrop.DisplacementduringtheWenchuanearthquakeishighlylocalizedwithinthefaultgougelayeralongnarrowerslipping-zonesofabout10to20mminwidth.Thisisanimportantconstraintforanalyzingthermalpressurization,animportantdynamicweakeningmechanismoffaults.Overlappingpatternsofstriationsonslickensidesurfacesuggestthatseismicslipatagiventimeoccurredinevennarrowerzoneofafewtoseveralmillimeters,sothatlocalizationofdeformationmusthaveoccurredwithinaslippingzoneduringcoseismicfaultmotion.Faultbrecciazonesareboundedbythinblackgougelayerscontainingamorphouscarbon.Faultgougecontainsilliteandchloriteminerals,butnotsmectite.Clayeyfaultgougenexttocoseismicslippingzonealsocontainsamorphouscarbonandsmallamountsofgraphite.ThestructuralobservationsandmineralogicaldataobtainedfromoutcropexposuresofthefaultzoneoftheWenchuanearthquakecanbecomparedwiththoseobtainedfromtheWFSD-1andWFSD-2boreholes,whichhavebeendrilledveryclosetotheHongkououtcrop.Thepresenceofcarbonandgr

简介：TheWenchuanearthquakecoseismicdeformationfieldisinferredfromthecoseismicdislocationdatabasedona3-DgeometricmodeloftheactivefaultsinSichuan-Yunnanregion.Thenthepotentialdislocationdisplacementisinvertedfromthedeformationfieldinthe3-Dgeometricmodel.Whilethefaults'slipvelocitiesareinvertedfromGPSandlevelingdata,whichcanbeusedasthelong-termslipvector.Afterthepotentialdislocationdisplacementsareprojectedtolong-termslipdirection,wehavegottheinfluenceofWenchuanearthquakeonactivefaultsinSichuan-Yunnanregion.TheresultsshowthatthenorthwesternsegmentofLongmenshanfault,thesouthernsegmentsofXianshuihefault,Anninghefault,Zemuhefault,northernandsouthernsegmentsofDaliangshanfault,Mabianfaultgotearthquakerisksadvancedof305,19,12,9.1and18,51yearsrespectivelyintheeasternpartofSichuanandYunnan.TheLijiang-Xiaojinhefault,Nujiangfault,Longling-Lancangfault,NantinghefaultandZhongdianfaultalsogotearthquakerisksadvancedinthewesternpartofSichuan-Yunnanregion.WhereasthenorthwesternsegmentofXianshuihefaultandXiaojiangfaultgotearthquakerisksreducedaftertheWenchuanearthquake.

简介：Significantpostseismicdeformationofthe2008MW7.9WenchuanearthquakehasbeenobservedfromGPSdataofthefirst14daysaftertheearthquake.Thepossiblemechanismsfortherapidpostseismicdeformationareassumedtobeafterslipontheearthquakeruptureplaneandviscoelasticrelaxationofcoseismicllystresschangeinthelowercrustoruppermantle.WefirstlyusetheconstrainedleastsquaresmethodtofindanafterslipmodelwhichcanfittheGPSdatabest.Theafterslipmodelcanexplainnear-fielddataverywellbutshowsconsiderablediscrepanciesinfittingfar-fielddata.Toestimatetheeffectduetotheviscoelasticrelaxationinthelowercrust,wethenignorethecontributionfromtheafterslipandattempttoinverttheviscositystructurebeneaththeLongmenshanfaultwheretheWenchuanearthquakeoccurredfromthepostseismicdeformationdata.Forthispurpose,weuseaviscoelasticmodelwitha2DgeometrybasedonthegeologicalandseismologicalobservationsandthecoseismicslipdistributionderivedfromthecoseismicGPSandInSARdata.Bymeansofagridsearchwefindthattheoptimumviscosityis9×1018Pa·sforthemiddle-lowercrustintheChengduBasin,4×1017Pa·sforthemiddle-lowercrustintheChuanxiPlateauand7×1017Pa·sforthelowvelocityzoneintheChuanxiplateau.Theviscoelasticmodelexplainsthepostseismicdeformationobservedinthefar-fieldsatisfactorily,butitisconsiderablyworsethantheafterslipmodelinfittingthenear-faultdata.Itsuggeststhereforeahybridmodelincludingbothafterslipandrelaxationeffects.Sincetheviscoelasticmodelproducesmainlythefar-fieldsurfacedeformationandhasfewerdegreeoffreedoms(threeviscosityparameters)thantheafterslipmodelwithahugenumberofsourceparameters,wefixtheviscositiystructureasobtainedbeforebutredeterminetheafterslipdistributionusingtheresidualdatafromtheviscoelasticmodeling.Theredeterminedafterslipdistributionbecomesphysicallymorereas

简介：根据中国地震局的统一部署,近几年多个省份开展了地震安全示范社区建设,从加强抗震设防到应急预案编制、志愿者队伍建设、宣传教育等各个方面都不同程度地开展了工作。但现有的地震安全示范社区建设还没有统一建设和评价标准,建设水平也有较大的差距,对于推进这一工作的开展十分不利。本文通过系统的资料收集和调研,结合在大连市开展的具体实践,对地震安全示范社区建设与研究现状进行了分析,综合各省市实践经验和行业管理办法,参考安全社区建设方面的标准和管理规定,给出了地震安全社区的定义、建设标准应包含的要素及主要内容,讨论了应用前景和可能存在的问题,为今后全国范围内进一步开展此项工作提供了依据,也为制定行业标准奠定了基础。

简介：TheregionaltectonicbackgroundandcharacteristicsofactivefaultsoftheYutianMS7.3earthquakeonFebruary12,2014arediscussedinthispaper.AftertheanalysisoftheepicenterareaoftheMS7.3earthquakein2014andthefocalmechanismsoftheformerstrongearthquakesaroundit,theauthorsdeducedthattheseismogenicfaultoftheMS7.3earthquakeistheeastbranchoftheAshikulefault.TheMS7.3earthquakein2014andtheMS7.3earthquakein2008aretwostrongearthquakeeventsonthedifferentsectionsoftheAltunTaghfault,wherethefaultbehaviorchangesfromsinistralsliptonormalfaultingbecauseoftheextensionaltaileffectsinthesouthernendoftheAltunTaghfault.ItisconcludedthatthetwoMS7.3earthquakeshavethesamedynamicsource,andtheMS7.3earthquakein2008promotedtheoccurrenceoftheMS7.3earthquakein2014.Finally,wecalculatetheCoulombstresschangetotheseismogenicfaultoftheMS7.3earthquakein2014fromtheMS7.3earthquakein2008usingthelayeredcrustmodel.TheresultalsoshowsthattheMS7.3earthquakein2008acceleratedtheoccurrenceoftheMS7.3earthquakein2014.

简介：StaticCoulombstresschangeinducedbyearthquakeslipisfrequentlyusedtoexplainearthquakeactivitiesandaftershockdistribution.However,someparametersfortheCoulombstresscalculationareunabletobewellconstrainedfromlaboratoryexperimentsandfieldobservations.DifferentparametersmaydirectlyaffectthepatternofstaticCoulombstress.ThestaticCoulombstresschangesinducedbytheWenchuanearthquakecalculatedbysixresearchgroupsarenotconsistentwitheachother.Toinvestigatehowtheparametersaffectthecalculationresults,wechangetheparametersinturnthroughmodelingandcomparetheresultsofdifferentcalculationparameters.Wefindthatgravity,positionandstrikeofreceiverfaultshavelittleinfluenceoncoseismicCoulombstresscalculations,butotherparameterscanchangethevalueandsignoftheresultsinvariousdegreesespeciallyaroundtheearthquakeruptureplane.ThereforetheuncertaintyanalysisofstaticCoulombstresschangeinducedbyearthquakeshouldbetakenintoconsiderationintheearthquakehazardanalysis.

简介：Micro-aftershockswithmagnituderangeof1.5-4aroundtheWenchuanearthquakeepicenter,thesouthernpartoftheLongmenshanfaultzone,exhibitgoodfrequency-magnitudelinearrelationships,thusenablingb-valueanalysis.Theaverageb-valueformicro-aftershocksofM1.5-4fromJulytoDecemberof2008inourlocalstudyregionisabout0.88,similartotheb-valueforallaftershocksofM3.0-5.5fromMay,2008toMay,2009alongthewholeLongmenshanfaultzone.Thesimilaritybetweenthelocalandregionalb-valuespossiblyindicatesthatthesouthernpartoftheLongmenshanfaultzonehassimilarseismogenicenvironmenttothewholeLongmenshanfaultzone.Alternatively,itmayalsoimplythatb-valuesderivedfromalleventswithoutconsiderationofstructuralvariationcannotdiscriminatelocal-scaletectonicinformation.Thepresentstudyshowsthattheb-valuefortheWenchuanearthquakemicro-aftershocksvarieswithdifferentregions.Theb-valueinsouthwestoftheYingxiutownishigherthanthatinthenortheastoftheYingxiutown.Thehighb-valueinthesouthwestpartwheretheWenchuanearthquakemainshockhypocenterlocatedindicatesthatthecurrentstressaroundthehypocenterregionismuchlowerthanitssurroundingarea.Theb-valuesarealsodependentondepth.Atshallowdepthsof<5km,theb-valuesareverysmall(~0.4),possiblybeingrelatedtostrongwaveattenuationorstrongheterogeneityinshallowlayerswithhighcontentofporosityandfractures.Atdepthsof~5-11km,wheremostaftershocksconcentrated,theb-valuesbecomeashighas~0.9-1.0.Atthedepthbelow~11km,theb-valuesdecreasewiththedepthincreasing,beingconsistentwithincreasingtectonichomogeneityandincreasingstresswithdepth.

简介：The2008Wenchuanearthquake,amajorintraplateearthquakewithMw7.9,occurredontheslowlydeformingLongmenshanfault.Tobetterunderstandthecausesofthisdevastatingearthquake,weneedknowledgeoftheregionalstressfieldandtheunderlyinggeodynamicprocesses.Here,wedeterminefocalmechanismsolutions(FMSs)ofthe2008Wenchuanearthquakesequence(WES)usingbothP-wavefirst-motionpolaritydataandSH/Pamplituderatio(AR)data.AsP-wavepolaritiesaremorereliableinformation,theyaregivenpriorityoverSH/PAR,thelatterofwhichareusedonlywhentheformerhaslooseconstraintontheFMSs.Wecollectdatafromthreecategories:(1)permanentstationsdeployedbytheChinaEarthquakeAdministration(CEA);(2)theWesternSichuanPassiveSeismicArray(WSPSA)deployedbyInstituteofGeology,CEA;(3)globalstationsfromIncorporatedResearchInstitutionsforSeismology.Finally,129eventswithmagnitudeoverMs4.0inthe2008WESareidentifiedtohavewell-constrainedFMSs.Amongthem,83arewellconstrainedbyP-wavepolaritiesonlyasshownbyCaietal.(EarthqSci24(1):115–125,2011),andtherestofwhicharenewlyconstrainedbyincorporatingSH/PAR.BasedonthespatialdistributionandFMSsoftheWES,wedrawfollowingconclusions:(1)theprinciplecompressionaldirectionsofmostFMSsoftheWESaresubhorizontal,generallyinagreementwiththeconclusiongivenbyCaietal.(2011)butwithafewmodificationsthatthecompressionaldirectionsareWNW–ESEaroundWenchuanandENE–WSWaroundQingchuan,respectively.ThesubhorizontalcompressionaldirectionalongtheLongmenshanfaultfromSWtoNEseemstohavealeftlateralrotation,whichagreeswellwithregionalstressfieldinvertedbyformerresearchers(e.g.,Xuetal.,ActaSeismolSin30(5),1987;ActaGeophysSin32(6),1989;Cuietal.,SeismolGeol27(2):234–242,2005);(2)theFMSsoftheeventsnotonlyreflectedtheregionalstressstateoftheLongmenshanregion,butalsowereobviouslycontrolledbythefaultstosomeextent,whichwaspointedou

简介：OnthebasisofthepreviousstudiesofthelayeredcrustalmodelintheYutianarea,combinedwiththefieldGPScontinuousobservationdata,weroughlyestimatetheviscouscoefficientofeachlayer.Withtheviscoelastichorizontallayermodel,wecalculatetheviscoelasticco-seismicCoulombstresschangecausedbytheYutianM_S7.3earthquakes2008and2014respectively.BasedontheCoulombstresschange,usingthecalculationmethodof"direct"aftershockfrequency,wecomeupwiththetheoreticalearthquakefrequencydirectlyrelatedtothemainshockandtheco-seismicCoulombstresschangeinthestudyarea.Thenweputforwardamethod,basedonthecomparisonoftheoreticalandactualearthquakefrequencyorthecomparisonbetweentheoreticalandpracticalearthquakefrequency-distancedecaycurvefittingresiduals,toestimatethemagnitudeofamaximumsequentearthquake,directlyrelatedtothemainshockco-seismicCoulombstresschange.Resultscalculatedbydifferentmethodsshowthatthemaximumfollow-upearthquakemagnitudecausedbythecoseismicCoulombstresschangeliesfromM_S7.2toM_S7.5followingYutianM_S7.3earthquakein2008;butthatofthe2014YutianM_S7.3earthquakeisM_S6.3.TheformerisveryclosetotheYutianM_S7.3earthquakein2014.Becauseofthesamemagnitude,relativelyclosespatialdistance,shorttimeinterval,thesameregionoftheexternalforce,thestrongcorrelationbetweentwoseismictectonicandaclearstressinteraction,wethusconsiderthatthetwoYutianM_S7.3earthquakesin2008and2014constituteapairofgeneralizeddoubleshocktypeearthquake.Thisisconsistentwiththesequencetypecharacteristicofpast"doubleshock"earthquakesintheregion.Inthispaper,theinfluenceofthemagnitudelowerlimitandtheb-valueintherelationshipofG-Rontheresultsisdiscussed.Asaresult,whentheviscoelasticcoseismicCoulombstressvariationisdetermined,thelowerlimitofmagnitudehaslittleeffectonthemaximumsequentearthquakemagnitude

简介：High-velocityfrictionexperimentswereconductedonclayeyfaultgougecollectedfromHongkououtcropofBeichuanfault,locatedatthesouthwesternpartofLongmenshanfaultsystemthatcausedthedisastrous2008Wenchuanearthquake.Theultimatepurposeofthisstudyistoreproducethisearthquakebymodelingbasedonmeasuredfrictionalproperties.Drygougeofabout1mminthicknesswasdeformeddryatslipratesof0.01to1.3m/sandatnormalstressesof0.61to3.04MPa,usingarotary-shearhigh-velocityfrictionaltestingmachine.Thegougedisplaysslipweakeningbehaviorasinitialpeakfrictiondecaystowardssteady-statevaluesafteragivendisplacement.Bothpeakfrictionandsteady-statefrictionremainhighatslowslipratesareexaminedandgougeonlyexhibitsdramaticweakeningathighsliprates,withsteady-statefrictioncoefficientvaluesofabout0.1to0.2.Specificfractureenergyrangesfrom1to4MN/minourresultsandthisisofthesameorderasseismicallydeterminedvalues.LowfrictioncoefficientsmeasuredonexperimentalfaultsareinbroadagreementwithlackofthermalanomalyobservedfromtemperaturemeasurementsinWFSD-1drillhole(WenchuanEarthquakeFaultScientificDrillingProject),whichcanbeexplainedbyevensmallerfrictioncoefficientfortheWenchuanearthquakefault.High-velocityfrictionexperimentswithporewaterneedstobedonetoseeifevensmallerfrictionisattainedornot.Shinyslickensidesurfacesformathighsliprates,butnotatslowsliprates.Slipzonewithslickensidesurfacechangesitscolortodarkbrownandformsduplex-likemicrostructures,whicharesimilartothosemicrostructuresfoundinthefaultgougesfromtheHongkououtcrop.DetailedcomparisonsbetweenexperimentallydeformedgougesamplesandWFSDdrillcoresinthefuturewillrevealhowmuchwecouldreproducethedynamicweakeningprocessesinoperationinfaultzonesduringWenchuanearthquakeatpresent.