简介:地震发生后,强震动观测台网可以获取灾区分布式台站位置的强震动记录,通过基于这些强震动记录得到的地震动参数可以快速地评估地震烈度的空间分布,以迅速判定不同地区的受灾程度,尤其是地震极震区的分布范围,为政府开展应急救援并合理地分配救援力量、物资等提供依据,以保证救援人员及时、准确地到达极震区展开搜救工作,减少人民群众的生命财产损失。本文介绍了国内外7种地震仪器的烈度计算方法,基于四川九寨沟M7.0级地震获取的强震动记录,对这7种方法的计算烈度值进行了对比分析。结果表明,各方法计算的仪器烈度与宏观烈度的差值均在1度误差范围以内,均显示了良好的实用性,且行业标准法和综合判别法两者的计算结果较为一致。
简介:Theconventionalpseudo-staticapproachoftenneglectstheeffectoftheverticalseismicaccelerationonthestabilityofaslope,butsomeanalysesunderplane-strain(2D)conditionsshowasignificanteffectontheslopestability.Thepurposeofthisstudyistoinvestigatetheeffectoftheverticalaccelerationonthesafetyofthree-dimensional(3D)slopes.Inthestrictframeworkoflimitanalysis,a3Dkinematicallyadmissiblerotationalfailuremechanismisadoptedherefor3Dhomogeneousslopesinfrictional/cohesivesoils.Asetofstabilitychartsispresentedinawiderangeofparametersfor3Dslopesundercombinedhorizontalandverticalseismicloadingconditions.Accountingfortheeffectsoftheverticalseismicacceleration,thedifferenceinsafetyfactorsfor3Dslopescanexceed10%,whichwillsignificantlyoverestimatethesafetyofthe3Dslopes.
简介:通过对涉县地磁台FHD质子矢量磁力仪信号线避开市电交流线路及缩短信号线长度试验,认为仪器的信号线过长对仪器的背景噪声有着较大的影响,缩短信号线的长度可以有效降低仪器的背景噪声。另外,信号线附近的市电交流线路对仪器的观测结果影响有限。
简介:TheseismicwaveformoftheYutianMS7.3earthquake,XinjiangonFebruary12,2014wasrecordedclearlyandcompletelybytheDigitalSeismicNetworksofXinjiang,Qinghai,Tibet,andXinjiangHotanarray,sothemethodofjointlocationbyregionalseismicnetworkandseismicarraycanbeusedtoaccuratelydeterminetheearthquakesourcelocation.Thefollowingtechnologieswereusedintheprocessoflocation:(1)WeselectedseismicstationsequallylocatedaroundtheepicenteroftheMS7.3earthquakewithanaverageintervalofabout15degreesintheinitiallocation.(2)TherecordingwaveformsofYutianseismicstationwererotatedtotheradialandtangentialdirectionstopreciselyobtainthearrivaltimeofS-wavestodeterminetheepicentraldistance.(3)Thevelocitymodelwasusedinthedeterminationoflocationoftheepicenter,basedonthehistoricalrecordsofearthquakesintheareawithinaradiusof1.0°fromthesourceasthecenter,andthevelocitymodelisobtainedafterre-fittingandcalibration.(4)BasedonthewaveformrecordsoftheHotanseismicarray,themethodofwaveformbeamingwasusedtodeterminetheazimuthsandperformthecorrectionoftheepicenterlocationwiththeseazimuths.(5)Thedeterministicmethodwasusedtomeasurethesourcedepth.Finally,itisconcludedthattheYutianMS7.3mainshockhypocenterlocationis36.197°N,82.467°E,focaldepth12kmandoriginaltime17:19:48.2p.m.February12,2014.
简介:本文选取山东地区2个Ⅲ类场地的工程地质勘探及土层剪切波速等资料,将土层厚度按5个深度段,每个分段给出了4个土层剪切波速的改变量,通过改变不同深度段土层剪切波速,建立了19种土层地震反应分析模型,分析了不同深度段,不同概率水平下土层剪切波速的变化对场地地震动参数的影响.研究表明,不同深度段土层剪切波速的变化对场地地震动参数的影响有差异.具体表现为,土层剪切波速的改变在1-10m、11-40m和地震输入界面处三个深度段对地震动加速度峰值影响较大;其中,41-70m和71-100m两个深度段剪切波速的改变对地震动加速度峰值影响小;在土层深度1-10m时,剪切波速降低,峰值变大,剪切波速的改变与峰值的改变呈负相关;在其它深度段,剪切波速降低,峰值变小,剪切波速的改变与峰值的改变呈正相关.剪切波速的改变在1-10m和11-40m两个深度段对地震加速度反应谱影响较大;在41-70m、71-100m和地震输入界面三个深度段对地震加速度反应谱影响很小.
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(ML)震源深度(Km)震中烈度 地震类型 198810310612119°29′25°39′1194°257°福清县城西南409Ⅴ孤立型 微观震中与宏观震中基本吻合,如图1所示,仅有4公里左右的偏离。二、地震烈度分布图12-1为根据现场调查所勾划出的地震等震线图。划分出Ⅴ、Ⅳ、Ⅲ三个烈度区。图12-1 1988年10月31日福建福清地震等震线图Ⅴ度区:为极震区。Ⅴ度等震线经过福清的龙溪,宏路,油圹,安民,柏渡等地,呈长轴北北东向的椭圆形,长轴长约17公里,短轴12公里,面积150平
简介:HistoricaldataregardingZhangHeng'sseismoscopeisnotsingularproof.Actually,thefourearliesthistoricaldocuments,i.e.,ContinuationofHistoriographyofHanDynasty,HistoriographyoftheLaterHan,BookoftheLaterHanandDingRecordallhaverelevantrecordsofitsstructure,size,principle,responsetoearthquakeandactualapplications.Thesefiveaspectsaresupportedbyarchaeologicalresearch,unearthedculturalrelics,historicalearthquakesandmodernseismologicalstudy.Thesehistoricalmaterialscontainagreatdealofspecificinformationaboutthisancientseismoscope.Inconclusion,theauthenticityandreliabilityofZhangHeng'sseismoscopeareverified.
简介:ThispapercalculatesthestaticCoulombstresschangesgeneratedbyfourearthquakesintheYutianareaduring2008~2014separately,thendiscussesthetriggeringinfluence,theiraccumulatedCoulombstresschangesandtheirinfluenceonnearbyfaults.TheresultsindicatethattheMS5.5earthquakein2011andtheM_S7.3earthquakein2014arebothintheregionswheretheCoulombstresschangeispositive,thestresschangesare0.004MPaand0.021MPa,respectively,meaningtheyaretriggeredbypriorearthquakes.TheMS6.2earthquakein2012occurredintheplacewhereCoulombstresschangewasnegative,soitispostponedbythepriorearthquakes.TheimageofCoulombstresschangesoftheMS7.3earthquakein2014isinaccordwithaftershocks(ML≥3.0)distribution,butsomeregionsonthefaultwheretheCoulombstresschangeispositivehavefewaftershocks,andstrongaftershocksmayoccuratthesedistrictsinfuture.Inaddition,thispapercalculatestheCoulombstresschangeonnearbyfaults,andfindsthattheCoulombstresschangesofdifferentelementsintheGGCfaultareverydifferent,andmustreceivestrongtriggered-influence,thoughtheresultmaybeinfluencedbytheinputfinitefaultmodel,sothereisstillalargeearthquake-risk.TheGGN,PLC,PLWandLBWfaultswerealsotriggeredbythefourearthquakesoccurringbetween2008~2014.TheirmaximumCoulombstresschangesallexceed0.002MPa,sotheyalsohaveastrongearthquakehazard.
简介:Preliminaryresultof3DgravitationalforwardcalculationstudyinBohaiSeaGUANGXIALIU1)(刘光夏)WENJUNZHAO2)(赵文俊)WENJUREN1)(任文菊)XIU...
简介:Theexperimentalresultsof3-Dfractureundercompressionareintroducedinbriefandthetheoryofstresscriterionof3-Dfractureisstudied.Methodstoimitateinitialfracturesaredeveloped.Itispointedthatthereareimportantdefectsintheextremevalue(EV)methodeverproposedbyPalaniswamyandKnauss.ThemajordefectliesinthatonlytwoEulerangles(2EA)areconsidered,butanotheroneisneglected.IfthevariationofallthethreeEulerangles(3EA)areconsidered,onecangetbetterresultwhichisconsistentwiththeobservationoffaultingthatextendsoncurvedsurfacesbutnotonplanes.Themethodofevaluatingmaximalnormalstressdirectionvector(NSDV)isproposedandfurtherprovedtobeequivalenttothe3EAmethod.ItisprovedthattheNSDVmethodcanbefurtheroptimizedtothemethodofcompositionofthefirstprincipaldifferentialplane(CFPDP).TheresultsfromCFPDPmethodcanfitthecurvedsurfacesofinitialgrowthobservedintheexperimentsof3-Dfracture.TheCFPDPmethodcanalsobeusedtointerpretthe3-Dfracturesoftheslippingsectionbetweentheasperitiesintheburiedfaultplanethatismodeledasellipsecrack.Theresultsof3-Dfracturecanbeappliedtointerpretingtherelatedproblemsoffaultingincludingthemechanismofalotofshatterrockswithdifferentdimensions,thecauseofearthquakesoccurredattheedgeofplateunderlowshearstress,andthemechanismofanisotropycausedbytheextensivedilatancyanisotropy(EDA)cracks.