2017年精河6.6级地震余震序列重新定位和发震构造

Relocation of the 2017 M_S6.6 Jinghe,Xinjiang earthquake sequence and its seismogenic structure

采用双差定位方法,利用中国地震台网的数据对2017年8月9日精河6.6级地震的余震序列进行了重新定位。截至2017年8月14日16时,共获得209个余震的重新定位结果。结果显示,余震主要呈近EW向或NWW向分布,余震区长约50km,宽约17km。余震分布在主震的西侧,推断此次地震单侧破裂。余震震源深度为1~25km,其中,震级较大余震深度为8~17km。精河地震序列的余震活动随时间呈起伏状衰减,震后2天内比较活跃,此后出现较快衰减。随时间推移,余震区呈现中西部衰减慢、东部衰减快的特点。此次地震震中距2011年精河5.0级地震震中21km,相比2011年精河地震,其震源更深,震级更大,但震源机制解相近,均为逆冲型。结合区域构造背景分析认为,库松木契克山前断裂为此次地震发震构造的可能性较大。

In this paper,the relocating of the aftershock sequence of the 2017 M_S6.6 Jinghe earthquake in Xinjiang was implemented using CENC data with the Double Difference relocation method. By the time of 16： 00 p.m. on August 14,2017,totally 209 aftershocks were relocated. It shows that the aftershocks are distributed along EW direction or NWW direction with the length of50 km and the width of 17 km. Since the most aftershocks are located at the western area of the epicenter,the main earthquake might rupture unilaterally from the east to the west. The hypocenters of the aftershock sequence ranges from 1 km to 25 km,among which most strong aftershocks range from 8 km to 17 km. The first 2 days after the mainshock is an active period of seismicity,after which it becomes inactive. Horizontally,the seismicity of the eastern aftershock area attenuates rapidly while the western area decays slower. The mainshock is much stronger and deeper compared with the 2011 M5.0 Jinghe earthquake which occurred 21 km away from this earthquake. But still the focal mechanism solutions of these two quakes are similar,and both are thrusting earthquakes. Considering the regional structure background,it is highly likely that the Kusongmuqike piedmont fault might be the causative structure of the earthquake.