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...

简介：ThisstudyproposesaGreen’sfunction,anessentialrepresentationofwater-saturatedgroundundermovingexcitation,tosimulategroundbornevibrationfromtrains.First,generalsolutionstothegoverningequationsofporoelasticmediumarederivedbymeansofintegraltransform.Secondly,thetransmissionandreflectionmatrixapproachisusedtoformulatetherelationshipbetweendisplacementandstressofthestratifiedground,whichresultsinthematrixoftheGreen’sfunction.ThentheGreen’sfunctioniscombinedintoatrain-track-groundmodel,andisverifiedbytypicalexamplesandafieldtest.Additionalsimulationsshowthatthecomputedgroundvibrationattenuatesfasterintheimmediatevicinityofthetrackthaninthesurroundingarea.Thewavelengthofwheel-railunevennesshasanotableeffectoncomputeddisplacementandporepressure.Thevariationofvibrationintensitywiththedepthofgroundissignificantlyinfluencedbythelayeringofthestratasoil.WhenthetrainspeedisequaltothevelocityoftheRayleighwave,theMachconeappearsinthesimulatedwavefield.TheproposedGreen’sfunctionisanappropriaterepresentationforalayeredgroundwithshallowgroundwatertable,andwillbehelpfultounderstandthedynamicresponsesofthegroundtocomplicatedmovingexcitation.

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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：江苏高邮、宝应Ms4．9级地震在极震区造成了数10间农村民居不同程度和不同方式的破坏，出现人员伤亡。震后对地震灾害现场进行震害调查与破坏原因研究，典型的震害特征包括砖砌体、砖木和砖混结构房屋局部倾倒、墙体贯通开裂、房顶瓦片掀翻和烟囱倒塌等。农村民居遭到破坏的主要因素包括：选址不当、施工质量较差、砂浆强度不够、缺少圈梁和构造柱等。同时，分析了竖向地震作用和鞭梢效应等地震效应，讨论了砖砌体和砖混结构抗震设计的加固方法和改善抗震性能的构造措施等，为农村民居的抗震设防和减轻震害损失等提供参考。

简介：EarthquakesofM_S5.6andM_S6.1occurredinYingjiang,YunnanonMay24andMay30,2014respectively.Inthispaper,weusethewaveformdatarecordedbymobileseismicstations(KAC)whichweresetupinthesourceareaaftertheYingjiangMS5.6earthquakeonMay24,2014tostudytheshear-wavesplittingcharacteristicsofYingjiangM_S6.1earthquakesequencewiththeSAMmethod.Theresultshowsthatpredominantpolarizationoffastshear-wavesbeforetheM_S6.1earthquakeisconsistentwiththedirectionofregionalprincipalcompressivestress,andpredominantpolarizationoffastshear-wavesbeforetheM_S6.1earthquakeshowbetterconsistencyandsmallerdispersioncomparedtoaftertheM_S6.1earthquake,andtheremaybeadeflectionforthefastshearwavespredominantpolarizationbetweentheM_S6.1earthquakesequenceandforeshocksequence.Wefoundthatthetime-delaysgenerallyexhibitedalowerlevelbeforetheM_S6.1earthquakeandarelativelyhighervalueaftertheM_S6.1earthquake.

简介：本文研究了1920年以来,云南地区M_s≥4.7级地震的时间序列及空间分布的特征标度。结果表明,当区内M_s≥4.7级地震在时间序列上出现我们定义的平静段和活跃段后,分别于418天和312天内即可能发生6级以上地震,对应率分别为71％和87％,1920年以来云南11次M_s≥6.8级地震前,出现活跃和平静特征标度的各5次。在空间上绝大多数(80％)大震震中处于我们所定义的长时间大范围空白缺震背景区或相对少震区内,仅少数(20％)位于4.7级以上地震相对密集区内或附近。4.7级以上地震上述时间序列及空间分布特征标度,可以作为云南6级,特别是6.8级以上地震中期或短期预测的判据和指标。同时可以看出,云南6级以上地震前,4.7级以上地震在时空演变上,经历了从无序到有序的演化过程。

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

简介：在地球旋转和1975Haicheng，辽宁Ms7.3地震，2008Wenchuan，四川Ms8.0地震和2004苏门答腊Msg之间的关系。在他们以前发生在震中区域附近的0地震，以及中等小的地震在这研究被调查。获得的结果能有益于在地球旋转和地震之间的关系的进一步的理解。

简介：OnJuly22,2013,theMinxian-ZhangxianM_S6.6earthquakeoccurredontheeastsegmentofLintan-Dangchangfault.TheanalysisofdigitalelevationandremotesensingimagingshowsthattheeastsegmentofLintan-Dangchangfaultisstillactiveandthemainthrustfeatureofthefaultswitchestoleftlateralslip.Withthefieldresearchofintensityanddamage,severalabnormalareasofdegreeⅧspreadintheisoseismallineofdegreeⅦandsomeabnormalareasofdegreeⅦspreadintheisoseismallineofdegreeⅥ.Theseabnormalareasaredistributedalongthehangingwallofthefaultinawidthof2km.TheanalysisbasedontheremotesensinganddigitalelevationmodelshowsthatthesegmentoftheLintan-DangchangfaultsouthofMinxianmainlyslipsinleftliteral.Thefaultmovementmadethesoilsoftinthefaultzone.Theearthquakemotionpropagatedalongthefaultzone.Thereforethestrongearthquakemotioncausedfoundationfailureinthesoftsoilalongthefaultzoneandtheabnormalintenseareasofdisasterformed.

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：本文收集了青藏高原区7级以上以走滑为主的30个地震的地表破裂参数资料,拟合出了青藏高原区新的震级与破裂带长度统计关系式,并结合前人的统计关系式,分别通过破裂带长度估算震级,求出了估算震级与仪器震级的差值。同时将差值为正值（即估算震级偏大）的归为一类,差值为负值（估算震级偏小）的归为另一类,做了分析和对比。研究发现,差值为正值的地震所处的走滑断裂带一般位于一级块体或次级块体的边界断裂带上;差值为负值的地震所处的走滑断裂带大多位于一级块体或次级块体内部断裂带或断裂带的交汇处。基于上述分类的差异,作者对不同回归关系计算的差值数据进行了统计分析,分别给出了修正计算结果不确定性的参考值,为降低估算震级的不确定性提供了理论依据。

简介：Alargeearthquake(MW=7.6)occurredinJiji(Chi-Chi),Taiwan,ChinaonSeptember20,1999,andwasfollowedbymanymoderate-sizeshocksinthefollowingdays.TwoofthelargestaftershockswiththemagnitudesofMW=6.1andMW=6.2,respectively,wereusedasempiricalGreen(sfunctions(EGFs)toobtainthesourcetimefunctions(STFs)ofthemainshockfromlong-periodwaveformdataoftheGlobalDigitalSeismographNetwork(GDSN)includingIRIS,GEOSCOPEandCDSN.FortheMW=6.1aftershockofSeptember22,therewere97pairsofphasesclearenoughfrom78recordingsof26stations;fortheMW=6.2aftershockofSeptember25,therewere81pairsofphasesclearenoughfrom72recordingsof24stations.Foreachstation,2typesofSTFswereretrieved,whicharecalledP-STFandS-STFduetobeingfromPandSphases,respectively.Totally,178STFindividualswereobtainedforsource-processanalysisofthemainshock.Itwasnoticedthat,ingeneral,STFsfrommostofthestationshadsimilaritiesexceptthatthoseinspecialazimuthslookeddifferentoroddduetothemechanismdifferencebetweenthemainshockandtheaftershocks;andindetail,theshapesoftheSTFsvariedwithazimuth.BothofthemreflectedthestabilityandreliabilityoftheretrievedSTFs.ThecomprehensiveanalysisofthoseSTFssuggestedthatthiseventconsistedoftwosub-events,thetotaldurationtimewasabout26s,andontheaverage,thesecondeventwasabout7slaterthanthefirstone,andthemoment-rateamplitudeofthefirsteventwasabout15%largerthanthatofthesecondone.

简介：Basedonwaveformdata,severalmethodstodeterminefocalmechanismsofsmallearthquakesweredevelopedsince1980.Kisslinger(1980)andJulian,Foulger(1996)proposedanapproachtodeterminesolutionbyusingamplituderatioofPandSwave.Schwartz(1995)devisedamethodtodeterminesolutionsbytheuseofpolaritydataandamplitudesofseismogramenvelopes.Amplitudesofshortperiodseismicwavespropagatinginaninhomogene-ousmediumaresensitivetothevariationinvelocityandQstructure.Nakamura,etal(1999)tookmediuminhomo-geneityintoaccountindeterminingfocalmechanismsofsmallearthquakesusingwaveformdata.Ifthelocationsofsmallearthquakesareconcentratedinasmallregion,wecanassumethattheraypathsfromtheeventstoagivenstationarealmostthesame.SoPandSwaveattenuationsareindependentofeventlocations.Inthiscaseitiscon-venienttodeterminefocalmechanismsoftheseeventsbyusingshortperiodPandSwavedataj.Focalmechanismsolutionsofsmallearthquakesin5regions,i.e.,Rongchang,Mabian-Muchuan,Ya￠an,BaoxingandMianzhu,whicharecoveredbytheChengduTelemeteredNetwork,areobtainedbyanalyzingthePpolarityandshortbodywaveamplitudedatarecordedinthenetworksince1992.AccordingtothemethodproposedbyGephartandForsyth(1984),basedonwelldeterminedfocalmechanismsolutionsin15sub-zonesofSichuanandYunnanarea,threeprincipalstresstensorss1,s2,ands3,insteadofaveragesofP,B,andTaxisofthesolutions,aredeterminedtorepresenttheregionalstressfielddistribution.