简介:BasedonthefirstarrivalPandSdataof4625regionalearthquakesrecordedat174stationsdispersedintheYunnanandSichuanProvinces,the3-Dvelocitystructureofcrustanduppermantleintheregionisdetermined,incorporatingwithpreviousdeepgeophysicaldata.Intheuppercrust,apositiveanomalyvelocityzoneexistsintheSichuanbasin,whereasanegativeanomalyvelocityzoneexistsinthewesternSichuanplateau.TheboundarybetweenthepositiveandnegativeanomalyzonesistheLongmenshanfaultzone.TheimagesoflowercrustanduppermantleintheLongmenshanfault,Xianshuihefault,Honghefaultandothersshowthecharacteristicoftectonicboundary,indicatingthatthefaultslikelypenetratetheMohodiscontinuity.Thenegativevelocityanomaliesatthedepthof50kmintheTengchongvolcanicareaandthePanxitectoniczoneappeartobeassociatedwiththetemperatureandcompositionvariationsintheuppermantle.TheoverallfeaturesofthecrustalandtheuppermantlestructuresintheSichuan-Yunnanregionaretheloweraveragevelocityinbothcrustanduppermostmantle,thelargecrustalthicknessvariations,andtheexistenceofhighconductivitylayerinthecrustor/anduppermantle,andhighergeothermalvalue.AllthesefeaturesarecloselyrelatedtothecollisionbetweentheIndiaandtheAsiaplates.ThecrustalvelocityintheSichuan-Yunnanrhombicblockgenerallyshowsnormalvalueorpositiveanomaly,whilethenegativeanomalyexistsintheareaalongthelargestrike-slipfaultsastheblockboundary.Itisconducivetothecrustalblockside-pressingoutalongthefaults.Inthemajorseismiczones,theseismicityisrelativetothenegativeanomalyvelocity.Moststrongearthquakesoccurredintheupper-midcrustwithpositiveanomalyornormalvelocity,wherethenegativeanomalyzonegenerallyexistsbelow.
简介:以伊朗巴姆地区为例,对伊朗巴姆地震造成的地表形变进行了差分干涉测量,得到了垂直向的同震三维形变场,并运用GIS三维分析技术对形变场进行了分析。实验结果表明,地震在巴姆城市的东侧造成了较大形变,在西侧也产生了微量形变。巴姆城市北部地块沉降,南部地块隆起。同时在巴姆城市南部可明显看到地震造成的断层。实验结果验证了基于C波段的SAR数据的D-InSAR技术在干燥地区监测地表形变方面的可行性。本文对产生去相关效应的原因进行了解释,认为对于干燥少植被的地区干涉效果较好。并指出,如果能够通过技术进步提高雷达干涉测量的精度并降低观测成本,同时将该技术与GPS、GIS等技术相结合,从而更好地研究形变机理,这将对地质灾害的研究产生重大意义。
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简介:Thispaperstudiesthree-dimensionaldiffractionofobliquelyincidentplaneSHwavesbytwininfinitelylongcylindricalcavitiesinlayeredporoelastichalf-spaceusingindirectboundaryelementmethod.Theapproachisvalidatedbycomparisonwiththeliterature,andtheeffectsofcavityinterval,incidentfrequency,andboundarydrainageconditiononthediffractionarestudiedthroughnumericalexamples.Itisshownthat,theinteractionbetweentwocavitiesissignificantandsurfacedisplacementpeaksbecomelargewhentwocavitiesareclose,andthesurfacedisplacementmaybesignificantlyamplifiedbytwincavities,andtheinfluencerangewithlargeamplificationcanbeaswideas40timesofthecavityradius.Surfacedisplacementsindryporoelasticcaseandsaturatedporoelasticcaseswithdrainedandundrainedboundariesareevidentlydifferentundercertaincircumstances,andthedifferencesmaybemuchlargerthanthoseinthefree-fieldresponse.
简介:这份报纸论述造的三故事的增强的水泥(RC)的一个所有框架模型的分析在1999台湾假装聪明的地震损坏了的三维的有限元素(FE)。尽管他们的贡献在设计被忽视,大楼的非结构的砖墙充当了一个地震抵抗元素。因此,一个典型框架的全部结构被建模,静态、动态的非线性的分析被进行评估砖墙的贡献。然而,分析的结果更加由于粗糙的网孔discretizations被过高估计,它由于有限计算机资源是不可避免的。这研究由修改改正overestimations(1)张力的力量并且(2)砍水泥和砖的僵硬减小因素。尽管,结果显示砖墙改进框架力量砍失败在列被引起由拱肩墙弄短。然后,三的有效性打字地震翻新被评估。一楼的最大的飘移被89.3%,94.8%,和27.5%减少由限制钢,Full-RC,和完整砖的模型分别地。最后,有土壤的模型的可行性分析被进行。分析显示土壤伸长尽管没有重要差别被观察,造的自然时期当模特儿。
简介:[BriefNews]:AnMs=7.3earthquakeoccurredinthesouthernAnMs=7.3earthquakeoccurredinthesouthernpartoftheTaiwanStrait(22.6°N,118.7°...