2022年青海门源M_(W)6.6地震发震构造——来自InSAR和高分影像约束  

Seismogenic structure of the 2022 Menyuan M_(W)6.6 earthquake,Qinghai Province,constrained by InSAR and Gaofen-7 observation

作　　者：许光煜 徐锡伟 易亚宁 温扬茂[3] 王启欣 李康 任俊杰 XU GuangYu;XU XiWei;YI YaNing;WEN YangMao;WANG QiXin;LI Kang;REN JunJie(National Institute of Natural Hazards,Ministry of Emergency Management of China,Beijing 100085,China;Faculty of Geomatics,East China University of Technology,Nanchang 330013,China;School of Geodesy and Geomatics,Wuhan University,Wuhan 430079,China)

机构地区：[1]应急管理部国家自然灾害防治研究院,北京100085 [2]东华理工大学测绘工程学院,南昌330013 [3]武汉大学测绘学院,武汉430079

出　　处：《地球物理学报》2022年第12期4704-4724,共21页Chinese Journal of Geophysics

基　　金：国家自然科学基金项目(U1839204,41941016,U2139201,41974004,42104008);应急管理部国家自然灾害防治研究院基本科研业务专项(ZDJ2017-24);中国博士后科学基金(2022M712703)联合资助.

摘　　要：2022年1月8日,在青海省门源县海原断裂带冷龙岭断裂西段和托莱山断裂东端发生了M_(W)6.6地震,发育了明显地震地表破裂带.本文基于欧空局哨兵1号雷达影像,利用InSAR技术获取了门源地震的同震形变场,升降轨InSAR同震视线向位移表现出相反的形变特征,量级达到~60 cm左右,同震形变存在非对称性分布特征,结合高分7号观测解译了近断层地表形变.利用InSAR观测反演获得了发震断层参数及详细滑动分布,计算了同震库仑应力变化,并对发震构造及震中区域未来地震危险性进行了分析讨论.结果表明:门源地震至少有两条断裂发生了破裂,主断层对应冷龙岭断裂西段,InSAR确定的最优断层模型显示主断层东段存在沿走向变化特征,西段则在地质解译断层基础上向西延伸,次断层对应地质解译的托莱山断裂东端,两个断裂组成一个平躺的Y型分布.断层最大滑动量约为~3.7 m,断层浅部存在滑动,表明该地震破裂到了地表,地表破裂长度约19 km.主断层滑动主要集中在0~9 km深度范围;次断层滑动主要集中在0~4 km深度范围,InSAR确定的矩震级为M_(W)6.6.库仑应力变化结果显示民乐—大马营断裂、托莱山断裂和冷龙岭断裂中段(即1927年古浪地震未破裂段)未来地震危险性不容忽视.On 8 January 2022,an M_(W)6.6 earthquake struck the Menyuan County,Qinghai Province.The epicenter of this earthquake is located in the western segment of the Lenglongling fault and east end of Tuolaishan fault,which belong to Haiyuan fault zone.Obvious surface rupture zone caused by this earthquake is developed.In this study,we use Sentinel-1 radar imagery to investigate coseismic deformation of this earthquake.Ascending and descending interferograms show opposite deformation across the fault zone that the relative motion is horizontal and related to strike-slip fault motion,with the magnitude of line-of-sight displacement of~60 cm.The main deformation feature is asymmetric.Surface deformation near fault is interpreted with Gaofen-7 satellite image acquired after earthquake.We then used Interferometric Synthetic Aperture Radar(InSAR)data to invert the fault parameters and detailed slip distribution of seismogenic fault,and calculated the coseismic Coulomb stress change.The complexity of seismogenic structure and future seismic risk of epicentre area are discussed.The inversion results suggest that at least two faults were involved in this earthquake.The main fault corresponds to the western segment of the Lenglongling fault.The optimal fault model determined by InSAR shows that the eastern section of the main fault changes along strike,while the western section extends westward along Lenglongling fault;the secondary fault corresponds to eastern end of Tuolaishan fault,and two faults form a lying Y-shaped layout.The majority of slip occurred between 0~9 km depth on the main fault,and 0~4 km depth on the secondary fault.The moment magnitude determined by InSAR is M_(W)6.6.The main features of slip on the main fault are:(1)maximum slip of~3.7 m;(2)slip reaches surface and ranges about 19 km.The results of coseismic Coulomb stress change show that the future seismic risk of Minle-Damaying fault,Tuolaishan fault and central section of Lenglongling fault(i.e.,the unbroken section of Gulang earthquake in 1927)should not

关 键 词：青海门源M_(W)6.6地震 同震滑动分布 INSAR 冷龙岭断裂 托莱山断裂 

分 类 号：P315[天文地球—地震学] P228[天文地球—固体地球物理学]