简介:ApplicationofcertaintyfactorsofearthquakeprecursoryanomalyevidencesCF(E)ZHAO-BIZHENG(郑兆),JUNZHANG(张军)andMEIQING(庆梅)Seismolo...
简介:CertaintyfactorsofearthquakeprecursoryanomalyevidencesCF(E)Zhao-BiZHENG(郑兆)(SeismologicalBureauofAnhuiProvince,Hefei230031,Ch...
简介:BecauseofthesignificancetotheformationandevolutionoftheTibetanplateau,thedisplacementandsliprateoftheAltynTaghfaulthavebeentopicsfullofdisputation.ScientistswhoholddifferentopinionsontheevolutionofTibetinsistondifferentslipratesanddisplacementsofthefaultzone.Inthearticle,studyisfocusedonthelateQuaternarysliprateoftheAltynTaghfaultwestoftheCherchenRiver(between85°Eand85°45'E).OnthebasisofhighresolutionSPOTimagesoftheregion,threesites,namelyKoramlik,AqqanpastureandDalakuansay,werechosenforfieldinvestigation.Tocalculatethesliprateofthefault,displacementofterraceswasmeasuredonSPOTsatelliteimagesorinsituduringfieldworkandthermo-luminescence(TL)datingmethodwasused.Togettheagesofterraces,samplesofsandwerecollectedfromtheuppermostsandbedsthatliejustunderloess.Themethodforcalculatingsliprateoffaultistodividethedisplacementofterracerisersbytheageofitsneighboringlowerterrace.Thedisplacementofriversisnotconsideredinthisarticlebecauseofitsuncertainties.AtKoramlik,thesliprateoftheAltynTaghfaultis11.6±2.6mm/asince6.02±0.47kaB.Pand9.6±2.6mm/asince15.76±1.19kaB.P.AtAqqanpasture,about30kmwestofKoramlik,thesliprateis12.1±1.9mm/asince2.06±0.16kaB.P.AtDalakuansayi,thesliprateofthefaultis12.2±3.0mm/asince4.91±0.39kaB.P.Hence,wegettheaveragesliprateof11.4±2.5mm/aforthewesternpartoftheAltynTaghFaultsinceHolocene.ThisresultisclosetothelatestresultsfromGPSresearch.
简介:一、地震基本参数表1 地震基本参数表发震时间年月日时分秒震 中 位 置微 观宏 观东经北纬东经北纬参考地名震级(MD)震源深度(Km)震中烈度 地震类型 1987080217071157°251°115°38′24°59′江西寻乌56178Ⅶ震群 微观震中与宏观震中不吻合,两者相距15Km左右,前者位于Ⅶ度极震区的外围的澄江附近。(图10-1)。图10-1 1987年8月2日寻乌地震等震线图二、地震烈度分布本次地震的宏观震中位于寻乌县城关北西3公里的文峰乡长举村附近,震中烈度Ⅶ度(图10-1)。Ⅶ度区(极震区):Ⅶ度等震线包围了寻乌县城关长宁镇及文峰乡的下河岭、黄坳、石圳、长溪和三标乡的的香
简介:Intheestimationofseismictendency,usingGutenberg-Richter¢sb-valueandusingHurstexponentaretwocom-monlyusedmethods.Basedonthefractalgeometryofearthquaketimeseries,wepointoutthatthesetwomethodscorrelatetoeachother.IntheperspectiveoffractionalBrownianmotion(FBM),anearthquakesequencewithb>3/4andthatwithb<3/4havedifferentdynamicproperties.
简介:Basedonisotropiclinearporoelastictheoryandundertheundrainedcondition,wesummarizethreeequationsconnectingtheSkempton’scoefficientBwiththegroundwaterlevel.Afteranalysis,weproposeamethodtocalculatetheSkempton’scoefficientBaccordingtotherelationshipbetweenwaterlevelandtidalstrain.WiththismethodwecangetthevalueofBwithouttheearthquakeoccurrence,whichcanprovidethehighfrequencywavesforresearch.Besides,wecanalsogetthein-suitSkempton’scoefficientBwithouttheexperimentofrockphysics.Inaddition,weanalyzetheobserveddataofChangpingstationrecordedingroundwatermonitoringnetwork(abv.,GMN)beforeandaftertheWenchuanMS8.0withthismethod,andfindoutthere’saslightchangeofthevalueofBaftertheseismicwavespassedby,whichimpliesthatthepropagationofseismicwavesmayhavebroughtsomevariationstotheporoelasticmediumofthewell.
简介:Inthisstudy,weadoptanimprovedBayesianapproachbasedonfree-knotB-splinebasestostudythespatialandtemporaldistributionoftheb-value.SynthetictestsshowthattheimprovedBayesianapproachhasasuperiorperformancecomparedtotheBayesianapproachaswellasthewidelyusedmaximumlikelihoodestimation(MLE)methodinfittingtherealvariationofb-values.WethenapplytheimprovedBayesianapproachtoNorthChinaandfindthattheb-valuehasaclearrelevancetoseismicity.Temporalchangesofb-valuesarealsoinvestigatedintwospecificareasofNorthChina.Weinterpretsharpdecreasesintheb-valuesasusefulmessagesinearthquakehazardanalysis.
简介:TheeffectsofmagnituderoundingandofthepresenceofnoiseintheroundedmagnitudesontheestimationoftheGutenberg–Richterb-valueareexplored,andthewaystocorrectfortheseeffectsareproposed.Fortypicalvalues,b=1androundingintervalDM=0.1,theroundingerrorisapproximately-10-3anditcanbecorrectedtoanegligibleapproximately-10-5.Forthesametypicalvalues,theeffectofnoisecanbelarger,dependingonthecharacteristicsofthenoisedistribution;fornormallydistributednoisewithstandarddeviationr=0.1,thecorrectb-valuemaybeunderestimatedbyafactor*0.97.
简介:一、地震基本参数表1 地震基本参数表发震时间年月日时分秒震 中 位 置微 观宏 观东经北纬东经北纬参考地名震级(MS)震源深度(Km)震中烈度 地震类型 9985200707119°18′24°49′惠安海外4811Ⅴ主余震型 地震发生于海域,离震中最近的惠安小山乍,距离约36公里。故宏观震中无考,震中烈度亦为推测的。二、地震烈度分布本次地震的现场调查工作,由莆田市、泉州市、南安市及惠安县等地震局(办)分开进行,各自提交有关调查报告。经过汇总及电话核查,给出本次地震的烈度分布图(图25-1)。其中Ⅳ度区是根据现场考察确定的,Ⅲ度线则是采取控制点电话调查的办法勾划的。图25-1 1999年8月
简介:[BriefNews]:AnMs=7.3earthquakeoccurredinthesouthernAnMs=7.3earthquakeoccurredinthesouthernpartoftheTaiwanStrait(22.6°N,118.7°...
简介:AmodelofseismicitywithfractalstructuresandapreliminarydiscussionontherelatiobetweenDandbvalueHat-KunJIANG(蒋海昆)andShou-ZhongDI...
简介:CumulativefrequencybvaluewithoutupperboundmagnitudeanditsregressiondeterminationJian-WenSHEN(沈建文)(SeismologicalBureauofAnhuiP...
简介:TheTanlu(Tancheng-Lujiang)faultisoneofthemajorstructuresineasternChina,whichcutsacrossdifferentblocksandcontrolsthetectonicactivity.UsingtheseismicdatafromtheChinaEarthquakeNetworksCenter,weinvestigatethespatialvariationsoftheb-valueintheDabie-Sulu(Jiangsu-Shandong)organicbeltbycalculatingtheb-valueofeachgrid(1°×1°)from1970to2010.Thestudyshowsthat:theb-valueissmallerintheTanlufaultanditsadjacentarea,whichmightsuggestthatthemajorearthquakerecurrenceperiodisrelativelylongduetothelowerfrequencyofsmallearthquakeactivity.InbothsidesofTanlufault,theb-valueishigherattheedgeofSulublockandtheeasternpartofDabieorogenicbelt.ThebvaluesarehigherinNorthChinacentralorogenicbelt,andsmallearthquakeactivitywhichoccurredalongthecentralorogenicbeltisfrequent.Additionally,combinedwithgeologicalandgeophysicalstudy,wefindthattheb-valuehasacertaincorrespondencerelationshipwiththelithologicdistribution,whichinformsusthatseismicactivityfeaturesarecloselyrelatedtotheinhomogeneousmediainthecrust.