2020年1月19日新疆伽师M_(S)6.4地震序列的活动特征和发震构造  

SEISMICITY FEATURE AND SEISMOGENIC FAULT OF THE M_(S)6.4 EARTHQUAKE SEQUENCE ON JANUARY 19,2020 IN JIASHI,XINJIANG

作　　者：崔仁胜[1,2] 赵翠萍[2] 周连庆[2] 陈阳[2] CUI Ren-sheng;ZHAO Cui-ping;ZHOU Lian-qing;CHEN Yang(Institute of Geophysics,China Earthquake Administration,Beijing 100081,China;Institute of Earthquake Forecasting,China Earthquake Administration,Beijing 100036,China)

机构地区：[1]中国地震局地球物理研究所,北京100081 [2]中国地震局地震预测研究所,北京100036

出　　处：《地震地质》2021年第2期329-344,共16页Seismology and Geology

基　　金：国家重点研发计划课题(2018YFC1503905-5);中国地震局地震预测研究所基本科研业务费专项(2018IEF010205,2018IES0401)共同资助。

摘　　要：文中利用新疆地震台网固定台站和流动台站的观测资料研究了2020年1月19日新疆伽师M_(S)6.4地震序列的活动特征和发震构造。重定位结果显示,地震序列呈NNW和近EW 2个优势方向分布,其中NNW向余震条带长约20km,近EW向余震条带长约40km。NNW向条带的发震断层倾角较陡,倾向W;近EW向条带的发震断层西侧倾角较陡,向E逐渐变缓,略S倾。M_(S)6.4主震深度为14.9km,地震序列优势分布于10~20km深度,近EW向的余震深度呈现由西向东逐渐变浅的特征。震源机制解结果表明,M_(S)6.4主震和2次5级以上余震的震源机制以逆冲为主,2020年1月18日M_(S)5.7前震以走滑为主。利用ISOLA方法对M_(S)6.4主震进行多源模型反演,结果显示主震由走滑和逆冲性质的2个子事件组成。推测M_(S)6.4地震发生在柯坪逆冲推覆构造带滑脱面以下的中下地壳,主震由NNW向W倾的高角度隐伏断裂和近EW向S倾构造先后破裂组成。The 2020 M_(S)6.4 Jiashi earthquake occurred on January 19,preceded by an M_(S)5.7 foreshock on January 18.These two earthquakes occurred close in space and time raising the question of the relationship between the two events.Using the observation data recorded by fixed stations and temporal stations of Xinjiang seismic network,the seismicity feature and the seismogenic fault of the Jiashi M_(S)6.4 earthquake sequence are studied in this paper.We relocated the Jiashi earthquake sequence from January 18 to August 31,2020,and obtained the relocations of 1-460 earthquakes by the double-difference algorithm.The high-precision earthquake catalog reveals detailed spatial and temporal evolution of the earthquake sequence.The relocations show that the M_(S)6.4 earthquake is located at 39.835°N,77.148°E,and the focal depth is 14.9km.The earthquake sequence is distributed in two dominant directions,one is NNW direction,the other is near EW direction.The length of the NNW earthquake belt is about 20km,and the length of the near EW earthquake belt is about 40km.The dip angle of the seismogenic fault of the NNW earthquake belt is steep,dipping to the west.The dip angle of the seismogenic fault of the near EW earthquake belt is steeper in the west,and gradually becomes more gentle from west to east,dipping to the south slightly.The main shock(M_(S)6.4)and the foreshocks including the M_(S)5.7 event occurred along the NNW earthquake belt.A large number of aftershocks occurred along the near EW earthquake belt,and two aftershocks above M5 occurred at the eastern side of the EW earthquake belt.The aftershocks on the south side of the main shock are rare,perhaps affected by the hard blocks of the Tarim Basin.The aftershocks distribution clearly illuminates a near EW-striking structure,likely the extension of the NNW-striking fault activated during the initial sequence.The dominant depth of the earthquake sequence is between 10km and 20km,the focal depth of aftershocks along the near EW direction is gradually shallower from west

关 键 词：伽师 M_(S)6.4地震 重定位 震源机制解 发震构造 

分 类 号：P315.2[天文地球—地震学]