基于Sentinel-1A数据的四川长宁MS6.0地震同震形变场分析及断层滑动分布反演

Coseismic Deformation and Fault Slip Inversion of the MS6.0 Earthquake Changning, Sichuan Based on Sentinel-1A Data

利用大地测量数据研究2019年6月17日四川长宁M_S6.0地震同震形变场特征和发震断层参数,基于DInSAR技术处理升降轨Sentinel-1A数据获取干涉相位图,并考虑大气折射效应和余震形变误差实现同震形变场改正。四叉树采样后的形变数据作为反演数据源,采用弹性半空间分层模型反演发震断层几何面滑动分布。结果表明本次地震发震机制为兼具逆冲和左旋走滑,矩震级为M_W5.9,断层破裂尺度达28 km×20 km,震源深度约9.4 km。升降轨视线向同震形变场在断层两侧呈现形变特征差异,最大沉降量分别是8.34 cm(升轨)和4.23 cm(降轨),最大抬升量分别是5.5 cm(升轨)和7.5 cm(降轨);发震断层走向为302°,倾角为43°,平均滑动角为50°,断层面最大滑动量达到0.28 m。

This paper uses geodesy method to study the coseismic deformation field characteristics and seismogenic fault parameters of the M_S6.0 earthquake in Changning,Sichuan on June 17,2019.The ascending and descending Sentinel-1 A data are processed to obtain the interferograms based on DInSAR technology,and to achieve coseismic deformation field correction by considering atmospheric refraction effect and deformation error caused by aftershocks.Based on the deformation data after quadtree sampling,the elastic half-space layered model is used to iteratively invert the slip distribution of the fault geometry.The results show a left-lateral strike-slip movement of seismogenic fault,the moment magnitude is M_W5.9,the fault rupture scale is 28 km×20 km,and the focal depth is about 9.4 km.The ascending and descending coseismic deformation fields indicate different deformation characteristics on the two sides of the fault,the maximum settlements are 8.34 cm(ascending)and 4.23 cm(descending),and the maximum uplifts are 5.5 cm(ascending)and 7.5 cm(descending)respectively.The strike of the seismogenic fault is 302°,the dip angle is 43°,the average slip angle is 50°,and the maximum slip of the fault plane is 0.28 m.