2016年运城4.4级地震序列精定位及发震构造分析

根据2016年运城4.4级地震序列资料，进行余震精定位、主震震源机制和发震构造等研究。地震震中分布结果显示，本次地震的发生构造与以往该地区震群型地震发震构造不同，构造单元相对简单，发生在盐湖北岸断裂附近。余震双差精定位结果显示，余震优势分布呈NNE向，NW向也有零星活动。精定位后震源深度集中分布在15-24 km，平均深度20.2 km，断层剖面深度集中分布在18-23 km，倾向NW，与盆地地形构造吻合。采用Snoke与CAP方法得到的震源机制解基本一致，此次序列的主震错断方式为走滑兼逆冲，节面B参数与中条山山前断裂东段走向和倾向接近。综合认为，本次运城地震序列的余震呈NNE向优势分布，精定位结合地震震源机制结果，推断此次地震序列发震断裂为中条山山前断裂的NNE向隐伏断裂。

Fine location and seismogenic structure analysis of Yuncheng M 4.4 earthquake sequence in 2016

In the paper, the aftershock relocation, mainshock focal mechanism solution and seismogenic structure of the Yuncheng M 4.4 earthquake sequence in 2016 are presented. The earthquake distribution results show that the Yuncheng M 4.4 earthquake sequence occurred near the Yanhu lake' northern shore fault which was located in simple structure and different from the seismogenic structure of previous swarm types. The aftershock relocation results show that most the preponderate distribution orientation of aftershocks is in NNE and scattered aftershocks distribute in NW. The focal depths after relocation concentrate on 15-24 km and the average depth is 20.2 km. The depths of fault section focus on 18-23 km and NW dip in accordance with the basin terrain structure. The focal mechanism solutions from Snoke and CAP methods are almost consistent, as slipping faulting with thrust strike. Nodal plane B result is close to the strike and dip of eastern Zhongtiaoshan fault. In summary, the aftershock distribution of Yuncheng earthquake sequence is mostly in NNE; Relocation and focal mechanism results refer that the sequence probably occur on the NNE buried fault of Zhongtiaoshan fault.