2017年九寨沟M_S7.0地震InSAR同震形变场与断层滑动分布反演

Fault Slip Distribution Inversion and Co-seismic Deformation of the 2017 Jiuzhaigou M_S7.0 Earthquake Based on InSAR

联合升、降轨Sentinel-1A卫星的差分干涉数据反演2017年8月8日四川九寨沟M_S7.0地震的断层滑动分布。首先对SAR复数干涉像对进行"二通"差分干涉处理,获取了覆盖震区的多视向InSAR同震形变场;然后利用四叉树和均匀采样法分别进行近、远场数据降采样,在此基础上,利用弹性半空间矩形位错模型,反演发震断层的几何参数和最优滑动分布。结果显示:(1)InSAR干涉条纹呈蝶状分布,最大LOS向沉降和抬升形变量分别为-20.3cm、11.3cm;(2)发震断层以左旋走滑为主兼有少量正断运动,断层走向为154°,倾角为82°;(3)断层滑动分布集中在2~15km深度,平均滑动角为-22°,最大滑移量约为0.68m,位于沿断层面深约9km处,地震释放的能量约为9.6×10^(18) N·m(M_W6.6),与测震学的研究结果基本一致。

An M S7.0 earthquake struck Jiuzhaigou,Sichuan province on 8 August 2017.This work obtained two LOS co-seismic measurements by carrying out the“Two-pass”differential interferometry on two tracks(1 ascending and 1 descending)of ERS sentinel-1A images firstly;Then the co-seismic displacements located in near and far field were subsampled with Quad-tree sampling and uniform sampling methods,respectively.The fault slip distributions were built based on the rectangular dislocation model in an elastic half space from the subsampled measurements.The results show that:①the both inteferograms display a similar butterfly shape caused by Jiuzhaigou earthquake,with the max amplitude of-20.3 cm and 11.3 cm,respectively.②The seismogenic fault is dominated by left-lateral strike with little normal faulting,with strike of 154°and dip of 82°.③The fault slip is mainly happened in the depth between 2 km and 15 km,with maximum slip of 0.68 m located at 9km depth,and the average rake of-22°.The moments released by the earthquake is about 9.6×10 18 Nm(M W6.6),which is almost consistent with the seismology research.