2015年新疆皮山MW6.4地震发震断层和滑动分布反演

doi:10.12196/j.issn.1000-3274.2020.01.007

摘要/Abstract

摘要： 本文基于Sentinel-1A卫星影像数据提取了2015年皮山M_W6.4地震的同震形变场, 震中北部以隆升为主, 最大抬升量为12.9 cm; 南部以沉降为主, 最大沉降量为5.5 cm。采用基于单一断层滑动模型的多峰粒子群优化和蒙特卡罗算法, 以LOS向InSAR形变场为约束, 对发震断层的几何模型进行非线性反演。在此基础上, 联合InSAR和GPS数据, 利用最速下降法反演断层滑动分布。综合结果表明: 发震断层是顶部埋深约7.4 km的隐伏断裂, 断层面大小为48 km×35 km, 断层走向、倾角、断层滑动角分别为111°、 19°、 91°; 断层最大滑动量0.47 m, 位于深度为10.6 km的区域; 累计地震矩3.89×10¹⁸ N·m, 约合矩震级M_W6.33。最后, 依据主震断层滑移量计算了主震对周围中小断裂的库仑应力扰动变化, 结果显示距离震中最近的泽普断裂受主震影响的库仑应力明显增加; 震后3年内余震集中分布在泽普断裂库仑应力增加区域, 表明皮山地震主震对余震的发生可能具有一定的应力触发作用。

关键词: 2015年皮山M_W6.4地震, InSAR, GPS, MPSO算法, 同震滑动分布, 库仑应力

Abstract: In this study, the coseismic deformation filed of the 2015 Pishan M_W6.4 earthquake is obtained using Sentinel-1A satellite data, the coseismic deformation filed shows an uplift on the north of the epicenter and subsidence in the south along the light of sight. The maximum uplift is 12.9 cm and the maximum subsidence is 5.5 cm. With the InSAR deformation measurements in the light of sight direction, we focused on the nonlinear inversion of the seismic fault geometry models by the Multipeaks Particle Swarm Optimization (MPSO) and Monte Carlo (MC) algorithms. Combining fault model parameters from the MC inversion algorithm and GPS coseismic deformation data the fault slip distributions were retrieved by the Steepest Descent Method (SDM). The comprehensive analysis of the results shows that the seismogenic fault of Pishan earthquake should be a hidden fault with the length is 48 km, the width is 35 km, the strike angle is 111°, the rake angle is 19°, the average rake angel is 91°, and the buried depth is about 7.4 km. The maximum slip of the fault is 0.47 cm located at the depth of 10.6 km. The cumulative seismic moment is 3.89×10¹⁸ N·m, approximately to M_W6.33. Finally, based on the fault slip of the main shock, we calculated the coulomb stress changed on surrounding faults, which shows the coulomb stress on Zepu fault exerted by the main shock increased significantly. The aftershocks for 3 years following the mainshock concentrate the zones where the coulomb stress increased, indicating that the main shock has a certain stress triggering effect on the occurrence of the local aftershocks.

Key words: Pishan Earthquake, InSAR, GPS, MPSO algorithm, Coseismic slip distribution, Coulomb stress

中图分类号:

P315.7

黄星, 洪顺英, 金红林, 刘泰, 董彦芳. 2015年新疆皮山M_W6.4地震发震断层和滑动分布反演[J]. 地震, 2020, 40(1): 84-98.

HUANG Xing, HONG Shun-ying, JIN Hong-lin, LIU Tai, DONG Yan-fang. Inversion of the Seismogenic Fault and Fault Slip Distribution of the 2015 Pishan M_W6.4 Earthquake[J]. EARTHQUAKE, 2020, 40(1): 84-98.

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