基于InSAR分析2015年尼泊尔M_W7.8地震形变场特征及断层滑动分布反演  

Analysis of Coseismic Displacements due to the M_W7.8 Nepal Earthquake Using InSAR Data and Inversion of Fault Slip Distribution

作　　者：徐小波 马超[2] 洪顺英[3] 连达军[1] 张迎峰[4] XU Xiao-bo;MA Chao;HONG Shun-ying;LIAN Da-jun;ZHANG Yingfeng(School of Environmental Science and Engineering,Suzhou University of Science and Technology,Suzhou 215009,China;School of Survesying and Iand Information Engineering,Henan Polytechnic University,Jiaozuo 454000,China;Institute of Earthquake Forecasting,CEA,Beijing 100036,China;State Key Laboratory of Earthquake Dynamics,Institute of Geology,China Earthquake Administration,Peijing 100029,China)

机构地区：[1]苏州科技大学,环境科学与工程学院,江苏苏州215009 [2]河南理工大学,测绘与国土信息工程学院,河南焦作454000 [3]中国地震局地震预测研究所,北京100036 [4]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

出　　处：《地震》2020年第4期76-89,共14页Earthquake

基　　金：国家自然科学基金项目(41701515);地震动力学国家重点实验室开放基金(LED2018B04)。

摘　　要：2015年4月25日尼泊尔发生了MW7.8地震,本文基于震前、震后两景Sentinel-1A雷达影像,采用D-InSAR两轨差分干涉法提取了此次地震的同震形变场。结果显示,同震形变场位于喜马拉雅造山带—主边界逆冲断裂(MBT)和主前锋逆冲断裂(MFT)附近,形变场整体表现为自西北向往东南方向延伸近150 km的纺锤形包络状,以大面积隆起抬升形变为主,视线向最大隆升形变达1.18 m,抬升区北侧存在一小沉陷区,以InSAR观测值定位同震最大形变中心。基于均匀介质弹性半空间模型(Okada模型)与InSAR观测数据反演了断层滑动分布。反演结果表明该地震属于典型逆冲型地震,发震断层为主喜马拉雅逆冲断裂(MHT),同震破裂从主喜马拉雅逆冲断裂(MHT)向上沿着主前锋逆冲断裂(MFT)传递。基于InSAR同震形变场局部形变细节,结合震区地质背景、断裂分布及断层运动特征,获得了同震破裂拟出露地表迹线。The Nepal M_W7.8 earthquake occurred on April 25,2015.Based on Sentinel-1 A SAR images before and after the earthquake,the coseismic deformation field was derived by D-InSAR method.InSAR observation results show that the coseismic deformation field was located near the Main Boundary Thrust Fault(MBT)and the Main Frontal Thrust Fault(MFT)in the Himalayan Orogenic Belt.The whole deformation field showed a spindle-shaped envelope extending about 150 km in length from northwest to southeast.The coseismic deformation is dominated by uplift in large area.The maximum uplift in line-of-sight(LOS)is 1.18 m.There was a small subsidence area to the north of the uplift area.The maximum coseismic deformation center is obtained from InSAR deformation.Based on the Okada model and InSAR observations,we inverted the fault slip distribution.Inversion results show that the earthquake is a typical thrusting event.The main seismogenic fault is Main Himalayan Thrust Fault(MHT).And coseismic rupture is transmitted upward from Main Himalayan Thrust Fault(MHT)along Main Frontal Thrust Fault(MFT).In this paper,based on the details of InSAR coseismic deformation field,combined with the geological background,fault distribution and fault movement characteristics of the earthquake area,the preliminary interpretation and description of the pseudo coseismic fracture surface trace is completed.

关 键 词：2015年尼泊尔M_W7.8地震 D-INSAR 同震形变场 滑动分布反演 

分 类 号：P315.7[天文地球—地震学]