基于光学遥感影像的2019年加利福尼亚M_(W)7.1和M_(W)6.4双震同震形变测量

Co-Seismic Deformation Measurement of 2019 M_(W)6.4 and M_(W)7.1 California Earthquakes Base on Optical Remote Sensing Images

利用地震前后的Landsat-8和Sentinel-2光学遥感影像数据,基于频率域互相关算法提取加利福尼亚州M_(W)7.1及M_(W)6.4地震的同震形变场,同时针对形变数据易受轨道误差、条带误差及时间失相干的影响,分别采用最小二乘多项式曲线拟合、改进均值相减等方法去除系统误差项。研究表明,M_(W)7.1主震以右旋走滑为主,地表形变的断层迹线呈NNW走向,长度达55 km,最大滑移量约为2.82 m;M_(W)6.4地震的发震断层迹线呈NE走向,长度达15 km,最大滑移量约为1.05 m,推测2次地震的发震断层分别为NNW向右旋走滑断裂及NE向左旋走滑断裂,二者形成典型的共轭关系。

The co-seismic deformation field of the M_(W)7.1 and M_(W)6.4 earthquakes in California is extracted using the frequency domain cross-correlation algorithm based on the Landsat-8 and Sentinel-2 optical images.At the same time,we use some error processing algorithms,such as the least square polynomial fit,the method of improved mean subtraction,and so on,to reduce the system errors often caused by orbit error,banding error and temporal decorrelation.The results show that the maximum slippage of the fault trajectory caused by the M_(W)6.4 foreshock is 1.05 m and the surface rupture trajectory is 15 km while the maximum surface slippage of M_(W)7.1 main shocks reaches 2.82 m and the surface fault trajectory is 55 km.We speculate that the two earthquakes formed a typical conjugate characteristic,which is controlled by NNW and NE strike-slip faults.