The Ms5.8 earthquake swarm occurred in Qian Gorlos Autonomous County,Jilin Province on October 31,2013.The earthquake is a rare swarm type in Song-Liao Basin.It's located on the intersection of Songyuan-Zhaodong fracture along NE direction and Chaganpao-Daozijing fracture along NW direction.Considering the seismogenic structure of this earthquake swarm is not clear,we relocated the hypocenters of 692 aftershocks based on double-difference earthquake location algorithm,and concluded that moderate aftershocks with M ≥ 3.0 have no opt-direction in space,while only small aftershocks have a NW opt-direction.We calculated,based on Coulomb Failure stress changes theory,the accumulated △CFS opt-solution of 4 M5.0 earthquakes both on NW focal plane and NE focal plane,and discussed the seismogenic structure by the analysis of spatial correlation between the pattern of △CFS opt-solution and relocated aftershocks.Our results show that △CFS opt-solution of the NW focal plane are positive on mainshock fracture,but opposite for the NE focal plane.And most △CFS values of NW focal plane on fracture reach the trigger threshold(0.01～ 0.10MPa),which controls the spatial pattern of most aftershocks.It is therefore concluded that Chaganpao-Daozijing fracture on NW direction plays a more important role in the evolution of Qian Gorlos earthquake swarm.%2013年10月31日在吉林省松原市前郭尔罗斯自治县发生了5级强震群活动(以下简称前郭震群),此次震群发生在NE向松原-肇东断裂和NW向查干泡-道字井断裂交汇处.由于震区未见明显的地表破裂,难以直接判断哪条断裂为主要的发震构造.为此,采用双差定位法对前郭余震序列692个地震事件进行重新定位,结果显示,3级以上强余震优势展布方向不明显,仅小震活动略呈NW向展布特征.由此,本文基于静态库仑应力触发理论,针对10月31日～1 1月23日的4次5级主震,分别以NW向和NE向作为发震面,计算了4次5级主震的叠加△CFS最优解,力图通过对△CFS最优解分布与重新定位后的余震活动分布的空间相关性分析,讨论前郭震群的发震构造.结果显示,沿NW向震源节面在研究区产生的库仑应力变化最优解分布在主震破裂面上显示为应力加载,NE向节面则显示为应力卸载,同时NW向的叠加△CFS最优解在震中区大部分位置达到经验触发阈值(0.01～0.10MPa),基本控制了全部的余震活动.由此,判断此次前郭强震群的主发震构造为NW向查干泡-道子井断裂的可能性较大.
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