Abstract: A lot of aftershocks will happen on and around the fault plane after big earthquakes. The spatial distribution of the aftershocks' position can precisely sketch the shape and position of the fault plane. Assuming that seismic fault can be simulated as a plane and most aftershocks would happen nearly around the fault plane, we can use the parameters of the aftershocks' position to estimate the strike, dip and position of the fault plane. We firstly use the aftershocks of the earthquake of M_S6.8 occurring in Jiashi region, Xinjiang Uygur Autonomous Region on February 24, 2003 to estimate the strike, dip and rake of the fault plane. According to the principle of the cluster of small earthquakes, we also try to use mathematical methods to screen data before inversing, and the more accurate inversion results validate the effectiveness of the proposed method.

Key words: Fault plane, Seismic fault, Stress field, Jiashi earthquake