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1、鲜水河—安宁河—则木河断裂带上可能存在的凹凸体:来自背景地震活动性的证据朱艾斓1,徐锡伟2,甘卫军2,陈桂华211上海市地震局,上海20006221中国地震局地质研究所,北京100029ZhuAilan1,XuXiwei2,GanWeijun2,ChenGuihua211EarthquakeAdministrationofShanghaiMunicipality,Shanghai200062,China21InstituteofGeology,ChinaEarthquakeAdministration,Beijing100029,ChinaZhuAil
2、an,XuXiwei,GanWeijun,etal1ThepossibleasperitiesontheXianshuihe2Anninghe2ZemuheFaultZone:Evidencefrombackgroundseismicity.EarthScienceFrontiers,2009,16(1):2182225Abstract:WemappedbvalueandlocalrecurrencetimeTLalongthe700kmlong,left2lateralstrikeslipXian2shuihe2Anninghe2Zemuhefaul
3、tzoneusingtherelocatedmicroseismicitybetween1992and2002thatprojectedontothecrosssectiontoidentifythepossiblelocationsofasperities1Strongvariationsinbvalueareobservedalongthestrikeofthefaultzone,whichareconsistentwiththesurfacefaultingsegmentationingeometry1Theanomalouslyshortloc
4、alrecurrencetimeTLandlowbvalueestimatesappearontheLuhuo2DaofusegmentoftheXianshuihefaultzone,theShimian2MianningsegmentoftheAnninghefaultzone,andtheXichang2PugesegmentoftheZemuhefaultzone,suggestingthatthesesegmentsmaybetherelativelyactivepartsthatpro2ducerelativelylargermicroea
5、rthquakesthanaverageduringtheinterseismicintervaltime1Withthehypothesisthatbvalueisinverselyproportionaltothestress,weinterpretthesethreesegmentsasthepossibleasperitiesonthefaultzone,wherethefuturemainshockwillbeinitiatedasthehighstresshasbeenaccumulatedthere1TheriskfromtheShimi
6、an2Mianningsegmentisespeciallynoticeable,whichisawell2knownhistoricearth2quakegap1TheanomalouslyhighbvalueandlongTLestimatesonthesoutheasternsegmentoftheXianshuihefaultzonealongQianning2Kangding2Shimiansuggestthatthissegmentmaybecreepingunderlowstressatpresent,andnonearfuturemai
7、nshockisexpected,althoughboththehistoricearthquakesandmicroseismicityareactivethere1Keywords:asperity;localrecurrencetimeTL;bvalue;theXianshuihe2Anninghe2Zemuhefaultzone;back2groundseismicity摘要:基于1992—2002年小震双差重新定位结果,沿鲜水河—安宁河—则木河断裂带走向的震源剖面作b值及局部复发时间TL值的空间扫描,以确定断裂带上可能存在的凹凸体。结果显示,
8、b值沿断裂带走向具明显的空间非均匀性,与地表几何结构的分段变异是相应的。异常短的TL值及低b值
