天山中段2次MS6.6地震前后库仑应力变化分析

ANALYSIS OF COULOMB STRESS CHANGE BEFORE AND AFTER TWO MS6.6 EARTHQUAKES IN MIDDLE TIANSHAN MOUNTAINS

2012年以来,天山中段相继发生了2次MS6.6地震,分别为2012年6月30日新源、和静交界MS6.6和2017年8月9日精河MS6.6地震。2次地震震中距为180 km。基于弹性和粘弹性模型相结合,采用2次地震的震源参数和断层分段模型数据进行库仑应力的计算,对2次地震后震源附近区域的库仑应力变化进行分析研究。同时分析精河MS6.6地震后对其周围断层的库仑应力变化影响。研究结果表明:(1)库尔勒以北、库车—新源区域均处于库仑应力正值区,2次MS6.6地震的发生对这些区域后续中强地震活动有促进作用;(2)北天山伊犁盆地北缘断裂、依连哈比尔尕断裂和博罗科努—阿其克库都克断裂处于精河MS6.6地震震后应力加载区。

An earthquake of MS6.6 occurred in Xinyuan and Hejing,Xinjiang,on June 30 th,2012,then another earthquake of MS6.6 occurred in Jinghe on August 9 th,2017.The distance between two earthquakes epicenter was 180 km.We used the focal mechanism solution and fault segment model data to calculate static coulomb stress based on the combination of elastic and viscoelastic models,analyzed and researched the influence of the stress change on the regional seismic activity for two strong earthquakes.We also made analysis of stress triggering effect of Jinghe earthquake with MS6.6 on surrounding areas and corresponding faults.The results showed that:(1)The area north of Kuerle and Kuche-Xinyuan were located in the positive Coulomb stress area,and the occurrence of two MS6.6 earthquakes had promoted the follow-up moderate-strong seismic activity in these areas.(2)The northern margin faults of Yili basin in northern Tianshan Mountains,the Yilian Habierga fault and the Borokunu-Aqikkuduk fault were located in the stress loading area after the Jinghe MS6.6 earthquake.