Precise location and seismogenic structure analysis of aftershock sequence of Jinghe M_S6.6 earthquake on August 9，2017

On August 9, 2017, an earthquake with M_S6.6 occurred in the Jinghe of Bortala Mongolia Autonomous Prefecture, Xinjiang, and the highest intensity is estimated up to Ⅷ, but no major surface ruptures had been observed in field survey. In order to determine the seismogenic structure of the Jinghe earthquake, this paper precisely locates the aftershocks occurred from the origin time of the main shock to December of 2017 in the source region by the double-difference location method. At the same time, the focal mechanism of the main shock is obtained by using the CAP waveform inversion method, and the focal mechanisms of some aftershocks are obtained by using the generalized polarization amplitude technology. The results show that the main shock is located at （44.27°N, 82.85°E） and the focal depth is 17 km. The aftershock sequence is located to the east of the main shock with focal depth of 33−18 km and an extending length nearly 30 km towards east. The predominant direction of the sequence is EW direction, and the subdominant direction is SW direction. The best double-couple solution of the main shock has one nodal plane with strike 260°, dip 51°, rake 84°, and the other nodal plane with strike 89.5°, dip 39.4°, rake 97.4°. The result suggests that the Jinghe earthquake is of thrusting type, and the focal mechanisms of a large number of small earthquakes obtained by inversion are consistent with that of the main shock. Combined with aftershock epicenters, focal mechanism solutions for the main shock and the aftershocks, as well as geological structure of the source region, it is inferred that the thrusted Kusongmuxieke piedmont fault extending in near EW direction is the seismogenic structure for the Jinghe main shock.