基于升降轨Sentinel-1 SAR数据研究2020年新疆于田MS6.4地震震源机制

2020年6月26日新疆于田县发生M_S6.4地震。 本文先利用Sentinel-1A/B卫星升、 降轨SAR数据, 结合InSAR技术提取此次地震的同震形变场; 并以同震形变场为约束, 利用贝叶斯方法的均匀滑动模型反演发震断层的几何参数; 最后基于梯度下降法(Steepest Decent Method, SDM)来确定发震断层更为精细的滑动分布。 研究结果表明: InSAR形变场的分布主要沿北北东方向, 东西方向跨度约40 km, 南北方向跨度约30 km, 形变特征为西侧沉降与东侧隆升, 西侧最大沉降约200 mm, 东侧最大隆升约70 mm。 于田地震发震断层为一条走向187.68°、 倾角59.78°、 滑动角77.76°的隐伏断层; 于田地震的宏观震源深度为6.29 km, 距震级M_W6.19。 断层滑动分布主要集中在沿走向7~21 km与倾向4~11 km的区域内, 平均滑动量约0.2 m, 在沿倾向7~8 km处的最大滑动量约0.97 m, 同震位错主要表现为正断运动。

The 2020 Ms6.4 Earthquake in Yutian Xinjiang Based on the Ascending and Descending Sentinel-1 SAR Data

The M_S6.4 earthquake occurred in Yutian County, Xinjiang, China on June 26, 2020. In this paper, the Sentinel-1A/B satellite’s ascending and descending SAR data are collected to extract the coseismic deformation field of this earthquake by using InSAR technology. Constrained by the coseismic deformation field, the geometric parameters of the seismogenic fault are obtained by using the uniform sliding model of Bayesian method. Finally, Steepest Decent Method (SDM) is used to determine the more delicate distribution of the fault. The results show that the deformation field of InSAR is mainly distributed along the North-North-East direction, with a span of about 40 km in the East-West direction and 30 km in the South-North direction. The deformation features are subsidence in the West and uplift in the East, with the maximum subsidence of about 200 mm in the West and the maximum uplift in the East of about 70 mm. The fault originated from the Yutian earthquake is a concealed fault with strike of 187.68°, dip angle of 59.78°and slip angle of 77.76°. The macro focal depth of Yutian earthquake is about 6.29 km, and the moment magnitude is M_W6.19. The fault slip distribution is mainly concentrated in the region of 7~12 km along the strike and 4~11 km along the trend, with the average slip momentum of about 0.2m and the maximum slip momentum of about 0.97 m at 7~8 km along the trend. The coseismic dislocation is mainly manifested as positive fault motion.