2016年新疆阿克陶MS6.7地震同震形变特征和断层滑动分布反演

本文针对2016年11月25日在新疆阿克陶发生的地震, 用差分干涉测量技术(D-InSAR)对3种不同观测模式的升、 降轨数据进行处理, 提取了多视线向的同震形变场; 根据不同模式的LOS向形变量, 构建形变分解模型, 将其分解为垂直向形变量和沿断层走向形变量; 结合同震形变场特征与震源机制解, 采用单断层模型, 利用梯度下降法(SDM), 以Multi-LOS向形变进行约束, 反演了阿克陶地震的同震滑动分布特征。 研究结果表明, 升、 降轨LOS向同震形变场在发震断层两侧具有不同的形变特征, 发震断层走向近EW向; LOS向形变量分解表明, 此次地震破裂以右旋走滑为主; 滑动分布反演的形变残差介于0~5 cm之间, 发震断层的滑动量主要位于2~16 km深部, 最大滑动量可达1.02 m, 位于断层面深部5.83 km处, 最大滑动量处的滑动角为185.24°; 平均滑动角为181.32°, 平均滑动量为0.12 m; 滑动分布反演也证明该地震为右旋走滑破裂事件, 与LOS向形变分解结果一致; 当剪切模量μ=3.2 GPa时, 反演得到的地震矩震级约M_W6.6。

Co-seismic Deformation Field and Inversion of Fault Slip Distribution of the 2016 Aketao MS6.7 Earthquake

Utilizing differential interferometric synthetic aperture radar technique, we retrieved multi-LOS co-seismic deformation field of the 2016 Aketao Ms6.7 earthquake through processing 3 kinds of different observation pattern data. According to the strike-slip characteristic of the fault, the fault-perpendicular deformation was neglected, and the up-down and fault-parallel deformation was extracted based on the combination of Sentinel-1A and Sentinel-1B observation. Besides, with the combination of deformation field features and focal mechanism solution, we inverted effectively the seismic slip distribution using the steepest descent method. The results demonstrate that the ascending and descending LOS co-seismic deformation fields have distinct different deformation characteristics on both sides of the seismogenic fault. According to the co-seismic deformation fields, the seismogenic fault is in the near east-west direction. According to the deformation fields, the earthquake is dextral strike-slip. The results of inversion demonstrate that the deformation residuals of the inversion are effectively controlled, which are basically between 0±5 cm. Fault slips distribute at the depth of 2 to 16 km. Results show that the maximum slip is 1.02 m at the depth of 5.83 km, and the rake angle is 185.24°. The mean slip is 0.12 m and the mean rake angle is 181.32 °.The rake angles at the two sliding distribution centers are close to 180 °. These demonstrate that the earthquake is a dextral strike-slip event, which is consistent with the result of LOS decomposition. When the shear modulus is set to 3.2 GPa, the retrieved seismic moment magnitude is M_W6.60.