2016年阿克陶M_(W)6.6地震的同震断层滑动分布及库伦应力变化

Co-seismic fault slip distribution and Coulomb stress change during the Aketao M_(W)6.6 earthquake,2016

2016年11月25日新疆阿克陶地区发生的M_(W)6.6地震,对当地人民生命造成一定的危害。基于Sentinel-1数据获取该地震的视线向同震形变场,采用贝叶斯方法反演单一断层走向为106.9°、倾角为73.8°、震源深度为17.35 km,在此断层几何模型基础上,以最速下降梯度法(Steepest Descent Method,SDM)反演滑动分布,结果表明断层面上存在两个滑动峰值,其中位于断层西侧的最大滑动量为0.66 m,深度为11.7 km,位于断层东侧的最大滑动量为0.83 m,深度为7.5 km,根据反演结果模拟LOS形变,其最大残差为~5 cm。构建倾角分别为70.79°和55.33°的双断层几何模型,并根据双断层几何模型反演了滑动分布,结果表明单一断层模型与双断层模型的滑动分布具有一致性,但是最大滑动量值有所不同,相对于单一断层模型的滑动分布而言,双断层模型的滑动量在西侧增大,其值为0.68 m;而在东侧减小,其值为0.77 m;最大残差降低了约2 cm。双断层模型库伦应力增加区域与余震的分布比较吻合。

On November 25,2016,an M_(W)6.6 earthquake occurred in Aketao region,Xinjiang.Based on the Sentinel-1 data,the line-of-sight co-seismic deformation field of the earthquake was obtained,and the Bayesian method was used to invert a single fault with a strike of 106.9°,a dip of 73.8°,and a focal depth of 17.35 km.On the basis of a geometric model of the fault,the slip distribution was inverted by the steepest descent method(SDM).The results showed that there are two slip peaks on the fault plane.The maximum slip on the west side of the fault is 0.66 m,with a depth of 11.7 km;the maximum slip on the east of the fault is 0.83 m,with a depth of 7.5 km.According to the inversion results,the LOS deformation was simulated,and the maximum residual error is~5 cm.A double-fault geometric model with dip angles of 70.79°and 55.33°was constructed to invert the slip distribution.The results showed that the slip distributions of the single-fault model and the double-fault model are consistent,but the maximum slip value is different.Relative to the slip distribution of the single-fault model,the slip of the double-fault model increases on the west side,with a value of 0.68 m;while it decreases on the east side,with a value of 0.77 m;the maximum residual error is reduced by~2 cm.The area of the Coulomb stress increase in the double-fault model matches the distribution of aftershocks.