2020年1月19日新疆伽师县M_(S)6.4级地震InSAR同震形变场与断层滑动分布反演  

Coseismic deformation and slip distribution of the M_(S)6.4 Jiashi,Xinjiang earthquake revealed by Sentinel-1A SAR imagery

作　　者：李成龙 张国宏[1] 单新建[1] 屈春燕[1] 龚文瑜[1] 贾蕊 赵德政 LI ChengLong;ZHANG GouHong;SHAN XinJian;QU ChunYan;GONG WenYu;JIA Rui;ZHAO DeZheng(State Key Laboratory of Earthquake Dynamics,Institute of Geology,China Earthquake Administration,Beijing 100029,China;School of Resource Environment and Earth Science,Yunnan University,Kunming 650091,China)

机构地区：[1]中国地震局地质研究所,地震动力学国家重点实验室,北京100029 [2]云南大学资源环境与地球科学学院,昆明650091

出　　处：《地球物理学进展》2021年第2期481-488,共8页Progress in Geophysics

基　　金：中央级公益性科研院所基本科研业务专项(IGCEA2001,IGCEA1919,IGCEA2005)资助.

摘　　要：利用欧空局Sentinel-1A SAR数据,重建了2020年1月19日新疆伽师县M_(S) 6.4地震InSAR同震形变场.以升降轨InSAR形变场联合约束,反演了发震断层参数与同震滑动分布.结果表明,地震同震形变场(长轴走向近EW向)发生在柯坪塔格褶皱带与奥兹格尔它乌褶皱带之间的区域内,升降轨观测的视线向(LOS)形变量相同,反映出发震断层运动性质是以逆冲为主,最大LOS向形变量约7 cm,干涉形变场呈现非对称性分布.断层模型反演结果显示,破裂区域长度为24 km,宽8 km,集中于地下深度4~6 km范围内,同震最大滑动量约0.34 m,平均滑动角85°,矩震级为M_(W) 6.0,北倾(倾角15°)逆冲推覆运动主导着断层破裂,兼具少量走滑运动分量.从发震断层模型、同震滑动深度分布及破裂运动学特征推测,这次伽师地震的发震构造是柯坪塔格褶皱带山前出露的柯坪塔格逆断裂,且支持柯坪塔格地区的薄皮构造模型.We reconstructed the coseismic deformation fields of the M_(S) 6.4 Jiashi,Xinjiang earthquake occurred on January 19,2020 utilized the ascending and descending SAR imagery(TOPS model)produced by Sentinel-1A satellite of EAS.Our results indicate that coseismic deformations of this earthquake represent an east-west shape,and ruptured between the Kepingtage and Aozigeertawu folding zone.The ascending and descending LOS deformations,with maximum LOS displacement of~7 cm,were highly consistent with each other,which corresponds to the ruptured characteristics of thrust faults on InSAR deformations.The deformation produced by InSAR is asymmetrical that more deformation is observed on the southern side of the rupture.It suggests that seismogenic fault plane dips to north.We further obtained kinematic parameter of fault and coseismic slip distribution jointly constrained by our ascending and descending deformations fields.The inversion results of fault model indicate that a 24 km×8 km main rupture zone concentrated in depth of 4~6 km,and the coseismic slip peaked about at 0.34 m with a mean rake angle of about 85°.The derived moment magnitude is M_(W) 6.0,consistent with published results from USGS.The coseismic rupture was predominated by over-thrust motion on a north-dipping fault(dip angle of 15°),with minor left-lateral strike-slip component.Overall,our result indicates that this Jiashi earthquake was triggered by the the Kepingtage fault,and the result interprets the Kepingtage thrust zone to have a thin-skinned structure.

关 键 词：伽师县地震 同震形变场 断层滑动分布 柯坪塔格褶皱带 

分 类 号：P315[天文地球—地震学]