摘要
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.
出版日期
2002年01月11日（中国期刊网平台首次上网日期，不代表论文的发表时间）
