简介:Thepost-earthquakerapidaccurateassessmentofmacroinfluenceofseismicgroundmotionisofsignificanceforearthquakeemergencyrelief,post-earthquakereconstructionandscientificresearch.TheseismicintensitydistributionmapreleasedbytheLushanearthquakefieldteamoftheChinaEarthquakeAdministration(CEA)fivedaysafterthestrongearthquake(M7.0)occurredinLushanCountyofSichuanYa’anCityat8:02onApril20,2013providesascientificbasisforemergencyrelief,economiclossassessmentandpost-earthquakereconstruction.Inthispaper,themeansforblindestimationofmacroscopicintensity,fieldestimationofmacrointensity,andreviewofintensity,aswellascorrespondingproblemsarediscussedindetail,andtheintensitydistributioncharacteristicsoftheLushan'4.20'M7.0earthquakeanditsinfluentialfactorsareanalyzed,providingareferenceforfutureseismicintensityassessments.
简介:TheWenchuanMS8.0earthquakeoccurredontheLongmenshanfaultwhichinclinesatadipangleexceeding60degrees.Sincemostthrustearthquakesoccuronfaultswithdipanglesofabout30degrees,itisenigmaticwhytheWenchuanearthquakeoccurredonsuchasteepfault.InthisstudyweuseasimplefiniteelementmodeltoinvestigatehowthestressstateinthefaultchangeswiththevariationofPoisson’sratio.Theresultsshowthat,withthePoisson’sratiointhefaultincreasing,themagnitudesoftheprincipalstressesincreaseandthemaximumshearstressdecrease,and,especially,theanglebetweenthemaximumprincipalstressandthefaultplanedecreases,whichwillenhancethedrivingforcetoovercomethefrictionalresistanceonthefault.TheincreaseofPoisson’sratiointhefaultmaybeanimportantfactortoaffecttheoccurrenceofthefaultearthquakeswithlargeanglesbetweenmaximumprincipalstressandfaultplane.
简介:TheYellowstonevolcanoisoneofthelargestactivevolcanoesintheworld,anditspotentialhazardsdemanddetailedseismologicalandgeodeticstudies.Previousstudieswithtraveltimetomographyandreceiverfunctionshaverevealedalow-velocitylayerinthecrustbeneaththeYellowstonevolcano,suggestingthepresenceofamagmachamberatdepth.Weuseambientseismicnoisefromregionalseismicstationstoretrieveshort-periodsurfacewavesandthenstudytheshallowshearvelocitystructureoftheYellowstoneregionbysurfacewavedispersionanalysis.WefirstobtainedacrustalmodeloftheareaoutsideoftheYellowstonevolcanoandthenconstructedanabsoluteshearwavevelocitystructureincombinationwithreceiverfunctionresultsforthecrustbeneaththeYellowstonevolcano.Thevelocitymodelshowsalow-velocitylayerwithshearvelocityataround1.3km/s,suggestingthatalarge-scalemagmachamberexistsatshallowlevelswithinthecrustoftheYellowstonevolcanicregion.
简介:Ingeneral,earthquakecyclerelatedtoearthquakefaultingcouldincludefourmajorprocesseswhichcouldbedescribedby(1)faultlocking,(2)self-accelerationornucleation(possibleforeshocks),(3)coseismicslip,and(4)post-stressrelaxationandafterslip.Asuddenstaticstresschange/perturbationinthesurroundingcrustcanadvance/delaythefaultinstabilityorfailuretimeandmodifyearthquakerates.Basedonasimpleone-dimensionalspring-sliderblockmodelwiththecombinationofrate-and-statedependentfrictionrelation,inthisstudy,wehaveapproximatelyderivedthesimpleanalyticalsolutionsofclockadvance/delayoffaultfailurescausedbyasuddenstaticCoulombstresschangeappliedinthedifferenttemporalevolutionperiodsduringanearthquakefaulting.Theresultshavebeenusedinthephysics-basedexplanationofdelayedcharacteristicearthquakeinParkfieldregion,California,inwhichthenextcharacteristicearthquakeofM6.0after1966occurredin2004insteadofaround1988accordingtoitscharacteristicreturnperiodof22years.Atthesametime,theanalyticalsolutionsalsoindicatethatthetimeadvance/delayinCoulombstresschangederivedbythedislocationmodelhasacertainlimitationandfundamentalflaw.Furthermore,wediscussedtheessentialdifferencebetweenrate-andstate-variableconstitutive(R–S)modelandCoulombstressmodelusedcommonlyincurrentearthquaketriggeringstudy,anddemonstratedthat,infact,theCoulombstressmodelcouldbeinvolvedintheR–Smodel.Theresults,wehaveobtainedinthisstudy,couldbeusedinthedevelopmentoftime-dependentfaultinteractionmodelandtheprobabilitycalculationrelatedtothetime-dependentandrenewalearthquakepredictionmodel.
简介:BasedonthesolutionsoftheGreen'sfunctionforasaturatedporousmediumobtainedbytheauthors,andusingtransformationofaxisymmetriccoordinates,Sommerfeldintegralsandsuperpositionoftheinfluencefieldonafreesurface,theauthorshaveobtaineddisplacementsolutionsofasaturatedporousmediumsubjectedtoatorsionalforceinahalf-space.Therelationshipcurvesofthedisplacementsolutionsandvariousparameters(permeability,frequency,etc.)underactionofaunitoftorquearealsogiveninthispaper.TheresultsareconsistentwithpreviousReissner'ssolutions,whereatwo-phasemediumdecaystoasingle-phasemedium.Thesolutionisusefulinsolvingrelevantdynamicproblemsofatwophasesaturatedmediuminengineering.
简介:OnApril25,2015,aM_S8.1earthquakeoccurredinNepal.IntheTibetareaofChina,thisearthquakecausedheavycasualtiesanddamagetohousing,roads,communications,otherlifelineengineering,waterconservancyandotherinfrastructure.Thispaperintroducesthebasicsituationoftheearthquake,andbasedontheinvestigationandassessmentofseismicintensity,thedamageofthedisasterareaisanalyzed,andbuildingtypesanddamagetothelifelinesystemsandvariousindustriesaregiven.Throughtheanalysisofthecharacteristicsoftheearthquakedisaster,thispaperpointsouttheexistingproblemsinseismicfortification,andfinallyputsforwardproposalsforthepreventionandcontrolofearthquakegeologicaldisasters,scientificplanningfortherestorationandreconstruction,strengtheningearthquakepreventionanddisasterreductionpropaganda,improvingtheawarenessofearthquakepreparednessintheagriculturalandpastoralareas,strengtheningtheguidanceandsupervisionofhousingconstructioninruralareastoreducethecasualtiesandlosses,andpromotingtheharmoniousdevelopmentofeconomyinTibet.
简介:Inordertodeterminethedegreeofreturning-to-zerooftemperaturesofdeformedcalcite,aseriesofrock-breakingexperimentsweredesignedtotestcalcite-richlimestonesamplesunderfixedconfiningpressuresanddifferenttemperatures.Theconsolidateddeformedsamplesintheirinitialstatewereobservedunderamicroscopeandthemicroscopicindicatorsindifferentzero-returningstateswereputforward,thusprovidingamicroscopicfoundationforevaluationofreliabilityofdatingvaluesofdeformationincalcite.Atlast,thecorrectionofdatingvaluesofdeformationforsampleswhosetemperaturehasnotyetreturnedtozeroisdiscussed.
简介:Inthispaper,basedonGansuDigitalSeismicNetworkdatasince1990,wecalculatedb-valueand⊿b-valueoftheneighborhoodareabeforethe2013Minxian-ZhangxianM_S6.6,earthquake.Theresultsshowthattheearthquakeoccurredatthemarginofthesignificantlylowerb-valueareainsoutheastofGansuandbeforetheearthquaketheneighborhoodareahadanobviouslyabnormal⊿b-value.Fromtheearthquakeandthespatialdistributionoflowb-value,theregionstillhasthepossibilityofgeneratingdangerousstrongearthquakes.
简介:汶川Ms8.0级地震发生在青藏高原东缘著名的龙门山断裂带上,造成了中央断裂和前山断裂共约330kin的地震地表破裂带。初步研究表明,龙门山断裂带上大震复发可能属特征地震模式。结合龙门山断裂带的地震地质情况和汶川地震地表破裂带的基本参数综合分析,本文从地质学、地震学和GPS数据分析三个方面评估了龙门山断裂带的大震复发周期。结果表明,上述三种方法获得的龙门山断裂带Ms8.0级地震的复发间隔分别为:3185a、170(02264a和4310a,平均为3000a左右:Ms7.5级地震的平均复发间隔为1000a左右;Ms7.0级地震的平均复发间隔为500a左右。这些结果与其他学者的研究结果相比,相差不多,基本反映了龙门山断裂带的地震能量水平和累积速度。
简介:Complex time-space spreading and focal mechanism of the 1989 Batang earthquake swarm (M_s=6.7)(程万正)(陈天长)Complextime-spacespre...
简介:BasedonthewaveformdataobservedbytheregionalseismicnetworkofGansuProvince,wecalculatedtheapparentstressof422earthquakeswithM_L≥2.0occurringinthesurroundingareaoftheMinxianearthquakefromJanuary2010toJuly2014andobtainedthetemporalandspatialvariationofapparentstressbeforeandaftertheMinxianearthquake.Resultsshowthat(1)thehighvalueofapparentstressofearthquakeswithM_L≥4.0wasconcentratedintheepicenterareabeforetheMinxianearthquakewhilethatofearthquakeswithM_L<4.0wasnot;(2)ApparentstressaroundtheepicenterareashowedanobviousincreasingprocessbeforetheMinxianearthquakeandtheincreasingprocesshascontinuedafterthemainshock,whichmeansthatthisstudyareaisstillinthedangerofstrongearthquakes.
简介:ThemodeserialsoftheEarth'sfreeoscillationprovidesomeimportantinformationontheEarth'sdeepstructureandsuperconductinggravimeters(SG)caninvestigatethephenomenaoftheEarth'sfreeoscillationswithhighaccuracy.ThegreatSumatra-AndamanearthquakefullyexcitedtheEarth'sfreeoscillationsandthesesignalswereperfectlyrecordedbyfivesuperconductinggravimetersintheglobe.Afterthepre-treatmentandspectralanalysisontheSGobservationdata,weobtainedtheexperimentedmodeserialsoftheEarth'sfreeoscillationsconsistingof147modeswithGGPstationdata.TheseobservedmodeswerethemselvessomenewimportantdataforthestudyoftheEarth'sdeepstructure.Onthebasisofthediscussionsonsomecheckedinner-core-sensitivemodes,wedistinguishedthreelayersfromtheinnercore,andtheboundaryoftheupperlayerwascompatiblewiththeformerlyknowntransitionzoneintheinnercorebasedonseismicbodywavesandsupportedthattherewerethehemisphericalvariationandverylowershearvelocityzoneinthelowerinnercore.
简介:TheHori’sinversemethodbasedonspectraldecompositionwasappliedtoestimatecoseismicslipdistributionontheruptureplaneofthe14November2001MS8.1KunlunearthquakebasedonGPSsurveyresults.TheinversionresultshowsthatthesixslidingmodelscanbeconstrainedbythecoseismicGPSdata.Theestablishedslipsmainlyconcentratedalongtheeasternsegmentofthefaultrupture,andthemaximummagnitudeisabout7m.Slipontheeasternsegmentofthefaultrupturerepresentsaspurelyleft-lateralstrike-slip.Sliponthewesternsegmentoftheseismicrupturerepresentsasmainlydip-slipwiththemaximumdip-slipabout1m.Totalpredictedscalarseismicmomentis5.196×1020N?m.Ourresultsconstrainedbygeodeticdataareconsistentwithseismologicalresults.
简介:IntroductionRegionalseismicitytriggeredbybigearthquakesaswellasattershocksinsourcezonecouldbedetectedduetothehighseismicmonitoringcapabilitytoday(Anderson,etal,1994;Bodin,Gomberg,1994;Caskey,Wesnousky,1997;Deng,Sykes,1996;Hill,etal,1993;King,etal,19...