基于InSAR形变观测反演2015年皮山M_S6.5地震滑动分布

Source Parameters and Slip Model of the 2015 Pishan M_S6.5 Earthquake Estimated from InSAR data

2015年7月3日在新疆皮山县发生了M_S6.5地震,该地震使当地遭受了巨大的经济损失。本文利用欧空局提供的Sentinel-1A卫星差分干涉数据对该地震的震源机制情况进行了反演研究,首先运用两轨法对卫星雷达影像进行差分干涉处理,获取了覆盖皮山地震震区的同震形变场,然后利用弹性半空间的均匀滑动模型反演获取了发震断层的几何参数,并对原始观测数据进行降采样处理,在此基础上运用分布式滑动模型反演获取了更为精细的断层滑动分布,结果显示分布式滑动模型与观测结果有很高的拟合度。反演结果表明发震断层是一个以逆冲为主兼有极少量左旋走滑的盲断层,此次地震断层面的同震活动分布主要集中在7~15km深度范围内,同震的地震矩为6.28×10^(18) N·m,矩震级为M_W6.46,与前人的研究结果非常一致。

On 3 July 2015, an Ms6. 5 earthquake occurred in Pishan County of Xinjiang, which caused huge local economic losses. We use interferometric synthetic aperture radar （InSAR） data from the European Space Agency＇s Sentinel-lA satellite to invert the focal mechanism solutions of the event. First of all, two-pass interferometry technique is uti- lized to obtain the coseismic deformation of the region which covers the whole epicenter of the Pishan earthquake. Secondly, we utilize the uniform slip model in elastic half-space to derive the geometric and kinematic parameters of the seismogenic fault, and after that we use the distributed slip model inversion method to obtain a more precise distribution of fault slip by means of down-sampling the original observation data. The results indicate that the inversion results are consistent with the observation data. In addition, the inver- sion results show that the seismogenic fault is the blind fault, which is dominated by thrust movement with a very small amount of sinistral slip. The fault slip is concentrated mainly in the depth between 7 km and 15 kin, the coseismic seismic moment is about 6.28×10^18N·m （Mw6.46）, which is consistent with the previous research.