简介：TheShanxiriftzoneisoneofthelargestandactiveCenozoicgrabensintheworld,studyingthevelocitystructureofthecrustanduppermantleinthisregionmayhelpustounderstandthemechanismsofriftprocessesandtheseismogenicenvironmentofactiveseismicityincontinentalrifts.Inthiswork,usingthebroadbandseismicdataofShanxi,Hebei,Henan,Shaanxiprovinces,andtheInnerMongoliaAutonomousRegionfromFebruary2009toNovember2011,wehavepickedout350high-qualityphasevelocitydispersioncurvesoffundamentalmodeRayleighwavesatperiodsfrom8to75s,andRayleighwavephasevelocitymapshavebeenconstructedfrom8to75speriodwithhorizontalresolutionrangingfrom40to50kmbytwo-stationsurface-wavetomography.Then,usingageneticalgorithm,a3Dshear-wavespeedmodelofthecrustanduppermostmantlehavebeenderivedfromthesemapswithaspatialresolutionof0.4°90.4°.Fourcharacteristicscanbeoutlinedfromtheresults:(1)ExceptintheDatongvolcaniczone,inthedepthrangeof11–30km,thelocationofatransitionzonebetweenthehigh-andlow-velocityregionsisinagreementwiththeseismicitypatterninthestudyregion,andtheearthquakesaremostlyconcentratednearthistransitionzone;(2)Inthedepthrangeof31–40km,shear-wavevelocitiesarehighertothesouthoftheTaiyuanBasinandlowertothenorth,whichissimilartothedistributionpatternofMohodepthvariationsintheShanxiregion;(3)Theshear-wavevelocitypatternofhighervelocitiestothesouthof38°Nandlowervelocitiestothenorthisfoundtobeconsistentwiththatfromtheuppercrustallevelstodepthof70km.Atthedeeperdepths,thespatialscaleofthelow-velocityanomalieszoneinthenorthisgraduallyshrinkingwithdepthincreasing,thelow-velocityanomaliesaregraduallydisappearingbeneaththeDatongvolcaniczoneatthedepthof151–200km.WeproposedthattherootoftheDatongvolcanomayreachtoadeptharound150km;(4)AlongtheN–

简介：Thispaperpresentsamodifiedhalf-sine-squaredloadmodelofthejumpingimpulsesforasingleperson.Themodelisbasedonadatabaseof22,921experimentallymeasuredsinglejumpingloadcyclesfrom100testsubjects.Threedimensionalmotioncapturetechnologyinconjunctionwithforceplateswasemployedintheexperimenttorecordjumpingloads.Thevariationrangeandprobabilitydistributionofthecontrollingparametersfortheloadmodelsuchastheimpactfactor,jumpingfrequencyandcontactratio,arediscussedusingtheexperimentaldata.Correlationrelationshipsbetweenthethreeparametersareinvestigated.Thecontactratioandjumpingfrequencyareidentifiedasindependentmodelparameters,andanempiricalfrequency-dependentfunctionisderivedfortheimpactfactor.Thefeasibilityoftheproposedloadmodelisestablishedbycomparingthesimulatedloadcurveswithmeasuredones,andbycomparingtheaccelerationresponsesofasingle-degree-of-freedomsystemtothesimulatedandmeasuredjumpingloads.Theresultsshowthatarealisticindividualjumpingloadcanbegeneratedbytheproposedmethod.Thiscanthenbeusedtoassessthedynamicresponseofassemblystructures.

简介：TheextensivedamagetobuildingscausedbytheNepalM_s8.1earthquakehasattractedmuchattentionbytheinternationalcommunity.AfterthepreliminaryscientificinvestigationsonthedifferentaffectedareasinNepal,theconstructionanddamagecharacteristicsoffivedifferenttypesofbuildingscommonlyexistinginNepalwerediscussedandthereasonsoftheirdisasterperformancewereanalyzed.Typesofbuildingsinvestigatedincludereinforcedconcrete(RC)framestructures,rubblestructures,brick-woodstructures,rawsoilstructures,andbrick-woodstructuresofhistoricbuildings.Inaddition,theweaklinksoftheseismicdesignwerepointedout,whichwasveryimportantforthepost-earthquakereconstructionandrecovery,andgaveapreliminaryexplanationsforthedamageexperienced.

简介：2014年11月15日,在甘肃省白银市景泰县发生MS4.7地震,震源深度10km。在震中附近200km以内,甘肃省地震局共安装架设有14台各类形变观测仪器。本文通过对这些形变观测仪产出的分钟值观测资料做小波分析发现,在地震前1个月内共有11台(套)形变观测仪记录到了异常变化。其中:SSY、TJ、DSQ、SSQ型观测仪记录到异常的同步性非常好;CZB型观测仪记录到的异常比较乱,没有固定的规律。通过对这些异常变化的总结能够为地震预测提供一定的判断依据。

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：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