简介：

简介：Becauseseismicactivitywithinmid-continentsisusuallymuchlowerthanthatalongplateboundaryzones,evensmallearthquakescancausewidespreadconcerns,especiallywhentheseeventsoccurinthesourceregionsofpreviouslargeearthquakes.However,thesesmallearthquakesmaybejustaftershocksthatcontinuefordecadesorevenlonger.TherecentseismicityintheTangshanregioninNorthChinaislikelyaftershocksofthe1976GreatTangshanearthquake.ThecurrentearthquakesequenceintheNewMadridseismiczoneincentralUnitedStates,whichincludesaclusterofM*7.0eventsin1811–1812andanumberofsimilareventsinthepastmillennium,isbelievedtoresultfromrecentfaultreactivationthatreleasespre-storedstrainenergyinthecrust.Ifso,thisearthquakesequenceissimilartoaftershocksinthattheratesofenergyreleaseshoulddecaywithtimeandthesequenceofearthquakeswilleventuallyend.WeusesimplephysicalanalysisandnumericalsimulationstoshowthatthecurrentsequenceoflargeearthquakesintheNewMadridfaultzoneislikelyendingorhasended.Recognizingthatmid-continentalearthquakeshavelongaftershocksequencesandcomplexspatiotemporaloccurrencesarecriticaltoimprovehazardassessments.

简介：

简介：Ontheconditionthatthevelocityratioofcompressivewavetoshearwaveisstableduringthepropagatingprocessofseismicwave,thispaperdevelopsanestimationmethodformediumqualityfactorbasedonsinglestation'straveltimedifferencebetweendirectSandPwavesandthefirstperiodsignalofdirectPwave.8774highSNRwavedataaltogetherrecordedby75stationsareanalyzed.Theresultsshowthat:(1)underthenormalregionalstressfield,thequalityfactorsQmSPinthestabletectonicareaarehigherthanthatintheactivetectonicareaaroundtheWeifang-JiashansectionanditssurroundingareaintheTanlufaultzone;(2)intheJuxian-Tanchengsectiontheseismicwaveattenuationisrelativelyquick,andthemediaisrelativelybroken,suggestingnotectonicstressaccumulation;(3)theXinyi-Sihongsectioniscurrentlylockingandinaccumulatingelasticstrainenergystage,whichhasthedeepenvironmentandconditionsofstrongearthquakegenerationsimilartothoseofthe1668M8.5Tanchengstrongearthquake.

简介：Accordingtofieldinvestigationandinterpretationofremotesensingimages,thenorthsegmentoftheLongling-RuilifaultisaHolocenedextralstrike-slipfaultwithasmallamountofnormalfaulting.Basedonlarge-scalegeologicalmappingatsometypicallocationsandquantitativegeomorphologicdeformationmeasurementanddatinganalysis,thisfaultisaHoloceneactivefault.Thestrike-sliprateoftheLongling-Ruilifaultis2.2~2.5mm/aandverticalsliprateis0.6mm/asincethelatePleistoceneepoch.Thestrike-sliprateoftheLongling-Ruilifaultis1.8~3.0mm/aandverticalsliprateis0.5mm/asincetheHoloceneepoch.BasedonthePoissonmodel,lognormalmodelandBPTmodel,theoccurrenceprobabilityofstrongearthquakesin50yearsisestimatedtobe6.32%,0.08%and0.05%,respectively.Then,a1.82%probabilityofoccurrenceofcharacteristicearthquakeforthenorthsegmentoftheLongling-Ruilifaultisobtainedbysettingaweightof0.28,0.36and0.36tothePoissonmodel,lognormalmodelandBPTmodel,respectively.

简介：Buisomg126earthquakefocalmechanismsolutions(Ms≥4.7)duringtheperiodof1963-1998,moderntectonicstressfieldinNorthChinaisinvertedbymeansofthestepbystepconv-ergence.Theinversionresultsindicatethatthetectonicstressfieldintheresearchregionisclearlyvariationalinspaceandtime:(1)Themiddlingprincipalstressaxisó2isbasicallyver-tical.Themaximumandminimumprincipalstressaxesó1andó2arenearlyhorizontal,buttheazimuthsofó1andó3areinconsistentindifferentdistrictsandperiods.(2)BeforetheTangshanearthquakein1976,thethreeprincipalstressaxesareuniform.Theazimuthofmaximumprincipalstressaxisó1is68°(strikinginaNEE-SWWdirection).(3)AftertheTangshanearthquake,themaximumprincipalstressaxisó1andminimumprincipalstressaxisó3havevariationsindifferentdistricts.InthenorthernareaofNorthChinaandontheeasternsideoftheTancheng-Lujiangfaultzone,themaximumprincipalstressaxisó1isalsostrikinginaNEE-SWWdirection.Itsazimuthis68°.ItistheasmeasthatbeforetheTangshanearth-quake.InthesouthernareaofNorthChina,themaximumprincipalstressaxisó1isstrikinginaE-Wdirectionanditsazimuthis87°.

简介：Ｃｒａｃｋ－ｉｎｄｕｃｅｄａｎｉｓｏｔｒｏｐｙｉｎｔｈｅｃｒｕｓｔｆｒｏｍｓｈｅａｒｗａｖｅｓｐｌｉｔｔｉｎｇｏｂｓｅｒｖｅｄｉｎＴａｎｇｓｈａｎｒｅｇｉｏｎ，ＮｏｒｔｈＣｈｉｎａＹｕａｎＧＡＯ（高原）Ｓｉ－ＨｕａＺＨＥＮＧ；（郑斯华）ａｎｄＹｏｎｇ...

简介：Beforeastrongearthquake,thereisoftenaprocessofquiescenceor2absence2ofregionalseismicactivity,whichisaphenomenonthathasattractedtheattentionofmanyscholarsinChinaandothercountries(LU,etal,1985;Wesson,1973).Inthepastten-oddyears,someChineseseismologistsmade,earlierorlater,specialstudiesonthequiescenceanomalyofseismicityinsomespecifiedareasfromdifferentangles.TakingtheconvertedannualfrequencyofM=5.0earthquakesinNorthChinaregionasacharacteristicquantity,JIANGandFENG(1989)analyzedthequiescenceanomalyofseismicactivitybyfuzzyrecognition.

简介：TakingtheHuaihetotheNvshanhusegmentoftheTanlu(Tancheng-Lujiang)faultzoneasthemainresearchtargettoexplorewhethertherehasbeennewactivitysincethelateQuaternary,andbasedontheinterpretationofremotesensingimagesandrepeatedsurfaceinvestigations,weexcavatedtrenchesatthesectionswherethetectoniclandformissignificant,identifiedandrecordedthedeformationpatternsofthefaultandanalyzedtheactivitybehavior.Samplesofnewactivityanddeformationwerecollectedandorientedslicesweregroundbasedonthesamples'originalstatetomakethemicrostructuralanalysisanddemonstration.Alloftheaboveresearchshowsveryclearlineartectonicgeomorphologyalongthefault,threetrenchesacrossthefaultzoneallrevealednewdeformationtracessincelateQuaternary.ThelateststratumdislocatedbythefaultisthelateQuaternaryandHolocene.Themainslipmodeisstickslip,asrepresentedtypicallybyfaultscarps,wedgeaccumulation,thefaultsandthefilledcracksandsoon.Ingeneral,itshowsthecharacteristicsofbrittlehigh-speeddeformationandbelongstotheprehistoricearthquakeruins.Theaboveunderstandingwasconfirmedpartiallybymicroscopicanalysis.Inaddition,thesimilaritiesanddifferencesandthepossiblereasonsforthecharacteristicsofthelatestactivitiesoftheTancheng-LujiangfaultzoneinthenorthandsouthoftheHuaiheRiverregionsarealsodiscussedinthispaper.

简介：Thetectonicconditionsforstrongearthquakesarecomplicatedinvariousaspects.Thegeneticconditionsforstrongearthquakeswerestudiedfromtheangleofvariousdisciplines.About20conditionsbelongingtodifferentfieldshavebeendescribedbypredecessors.Inthispaper,theauthorstrytostudyandevaluateallthetectonicconditionfactorsforstrongearthquakesbythemethodsoffuzzymathematicsandhierarchicalanalysis.TakingthenorthernpartofNorthChinaasanexample,theauthorsmakeacomprehensivedigitalanalysisofallthequantitativeandsemi-quantitativetectonicfactors.Thecredibilityvaluesofallstrongearthquakeswithdifferentmagnitudesaregivenafterstatisticalanalysisandcalculation.Forty-onefaultzonesinthestudyregionarequantitativelyanalyzed,andthepotentialseismogenicfaultzones,maximummagnitude,andriskofearthquakeoccurrenceinthenearfutureareassessed.Theresultofsyntheticevaluation,basedonalltectonicconditionsofdifferentcategorie

简介：Inordertounifythetimeandthespaceattributesintotemporal-spatialdistance,thetemporal-spatialproportionalcoefficientfTSisproposedinthispaper.Inaccordancewiththenewdistanceconcept,thetemporal-spatialcorrelativitywithintemporaldoubletsofstrongearthquakesinNorthChinaanditsvicinitysinceAD1500hasbeenanalyzed.ThecomputationresultsindicatethatdoubletsofstrongearthquakecanbedividedintotwogroupswhenfTSisendowedwith10km/ainthenewdistanceformula.Thetemporal-spatialdistancebetweentwopointsofdoubletgenerallycannotexceed140kmwhentwostrongquakesindoublethavesomecausativerelation.Andthosedoubletswithtemporal-spatialdistanceexceeding280kmareprobablyindependentseismiceventsindoublets.Thischaractercanbethereferencetothemigrationlawsummarizationandtrendprediction.

简介：Onthebasisoftheviewpointofpreparationofstrongearthquakesingroup,thespatialandtemporalscanningcharacteristicsoftheseismicityintheSouthYellowSeaanditscoastregionarestudied,andsomeproblemsregardingthepredictionofseismichazardarealsodiscussed.TheresultsshowthattheseismicactivityofM=4.0earthquakeshasoverallpresentedarelativestablestate,butthepartiallyconcentratedareawbichevolvesandmigratesandtheanomalouslowb-valueareahaveappearedindifferentperiods,andthemoderatelystrongearthquakeswithM=5.0～6.0havetakenplaceontheedgeoftheanomalousarea.TheaccumulativefrequencyofM=4.0earthquakesintheanomalousareapresentsnon-linearindexaccelerationandthemoderatelystrongearthquakeshaveappearedinthelateperiodofthenon-linearindexaccelerationofM=4.0earthquakesorinthelateranomaloustranquilperiotl.ThespatialandtemporalunevenPhenomenonofseismicityhassomestabilityandreproducibility,andhassom

简介：Usingthreedimensional(3D)viscoelasticfiniteelementmethod(FEM)westudythedynamicevolutionpatternofthecoseismicchangeofCoulombfailurestressandpostseismicchange,ontimescaleofhundredsyears,ofrheologicaleffectinducedbytheMS=7.2XingtaiearthquakeonMarch22,1966.Then,wesimulatethecoseismicdisturbanceinstressfieldinNorthChinaanddynamicchangerateonone-yearscalecausedbytheXingtaiearth-quakeandTangshanearthquakeduring15yearsfrom1966to1980.Finally,wediscussthetriggeringofastrongearthquaketoanotherfuturestrongearthquake.

简介：Athree-dimensionalcrustaldensitymodelbeneathNorthChinaisdeterminedusingP-wavetraveltimesandgravitydatumbysequentialinversionmethodinthispaper.Toimprovetheuniquenessofthesolution,weusedalinearrelationshipbetweenvelocityanddensitytoachievemutualconversionsandconstraintsbetweenvelocitydifferenceanddensitydifference.Algebraicreconstructiontechnique(ART)wasusedindensityinversion,whichhighlyimprovedthecalculationspeedcomparingwithcommonleastsquaresmethod.TheinversionresultsindicatethatthecrustaldensitybeneathNorthChinaisextremelyinhomogeneouswithitsdistributioncoherentwithregionaltectonics.ThelowercrustofTaihangmountaintectoniczoneshowsanobviouslowdensitycharacteristic.Weproposedthatitmaybeanindicatorofupwellingofmantlematerialsorpartialmeltingoflowermostcrust.

简介：Accordingtostudiesofmorethan20earthquakeswithMS≥5.0inNorthChina,sevenfeaturesoftheshort-termandimminentearthquakeprecursorshavebeensummarizedinthispaper.Atthesametime,takingtheshort-termandimminentearthquakestageasthephysicalprocessofasource’smediumsofteningandfaultcreep,wecalculatedtemporalvariationofmeanstress,maximumshearstress,bodystrain,andporepressureinsomecertainpoints(supposedstations)inthesourceareaanditsadjacentareabyusingananisotropicandnonlinearsourcemodelandafiniteelementmethod.Accordingtoananalysisofthesetheoreticalcurves,weconcludethattheshort-termandimminentearthquakeprecursorshavesuchcharacteristicsascomplexshapes,exponentialgrowthoftheprecursornumberwithtune,andprecursors’migrationfromtheoutsideareatothesourcearea,whichtoacertainextentrevealthecauseofthecharacteristicsoftheshort-termandimminentearthquakeprecursorfield.

简介：Longling-Ruili差错是在西南的中国的一个重要活跃差错，向东北通常罢工。差错沿着它在Longling盆，Mangshi盆和Zhefang盆的它的二个方面，以及发展上控制沉积系列和magmatic行动的发展。由于有限第四级的沉积和严厉自然条件，Longling-Ruili差错的北片断上的近来第四级的差错活动正在缺乏的学习和最新的指责的时间并且第四级滑倒率不目前是清楚的。基于遥远的图象的解释，量的geomorphologic变丑大小并且年轻平台存款和冲积扇子，标明日期这份报纸如下获得一些新结果。Longling-Ruili差错的北片断是有正常的某部件的一个Holocene右罢工滑倒差错滑倒。主要在4kaB.P期间形成的冲积存款创作的平台T1。是由Longling-Ruili差错的北片断的偏移量并且它的左侧面并且它的垂直排水量分别地是8m12m和2m。迟了的更新世冲积扇子分别地与70m和18m的左侧面、垂直的排水量被代替。Longling-Ruili差错的罢工滑倒率是2.2mm/a2。5mm/a并且垂直滑倒率是0。6mm/a自从迟了的更新世时代。Longling-Ruili差错的罢工滑倒率是1.8mm/a3.0mm/a并且垂直滑倒率在Holocene时代期间是0.5mm/a。比例对垂直排水量水平是大约4：1，它意味着垂直在Longling-Ruili差错的北片断上滑动率是大约25%水平滑倒率。左侧面在迟了的Holocene滑动率与GPS测量一致。罢工滑倒自从迟了的更新世时代，率具有在不同时间规模的大一致性，显示Longling-Ruili的活动指责稳定性大。

简介：