Abstract:On August 9, 2017, an MS6.6 earthquake occurred in Jinghe County, Xinjiang, China, and its epicenter was at 44.27°N, 82.89°E. Based on the broadband waveform recorded by the Xinjiang Seismic Network, we used the cut-and-paste method to invert the focal mechanism solutions of the main shock and 14 MS ≥ 3 aftershocks. Additionally, the stress field in the source area was inverted using MSATSI software. According to the focal mechanism solutions and surrounding geological data, we infer that the seismogenic fault is the eastern segment of the Kusongmuqike piedmont fault, and we identified nodal plane I with a strike of 89°, dip of 43°, and rake of 91ås seismogenic fault plane of the main shock. Of the 14 aftershocks, 11 were the thrust type, one was a normal faulting type, and two were the strike-slip type. The P axis is concentrated in the near N-S direction and has a small inclination angle, whereas the inclination angle of the T axis is large. This indicates that the stress field of the source region is characterized by a nearly N-S horizontal compression. The focal depths of the MS6.6 earthquake sequence ranged from 12 to 21 km, but were concentrated in the range of 15-20 km; thus, they were slightly shallower than the focal depth (21 km) of the main shock. The inversion result of the stress field in the source area accords with the statistical results of the focal mechanism parameters; thus, both indicate that the source area is mainly controlled by the horizontal stress field in the near N-S direction.
