关键词: 双差定位法, 震源机制解, 渭河-运城盆地, 构造应力场

Abstract: Based on the seismic phase report data of Weihe-Yuncheng Basin from January 2009 to June 2018, the repositioning results of 8,106 seismic events were obtained by using the double-difference location algorithm. Finally,we got valid locations for 8106 earthquakes. Meanwhile, we determined 346 focal mechanism solutions for earthquakes (ML≥2) by the grid search method.Then we inverted the fine crustal stress field of 1° × 1° grid in this region by MSATSI software package based on the focal mechanism solutions and the method of damped stress tensor inversion.The results show that the seismic events are distributed along the fault strike in the plane after relocation. It is densely distributed along the fault plane in vertical direction. The fault plane in this region has a large dip Angle, even nearly vertical, which is similar to the surface occurrence. The fault movement properties and focal mechanism solutions indicate that the fault properties in the study area are mainly normal fault and strike-slip. Stress field inversion results indicate that the maximum horizontal stress direction in Weihe fault depression belt is nearly EW in Weihe fault depression belt, and NNE and NEE in the south of Shanxi fault depression belt.

Key words: double-difference location, focal mechanism solutions, Weihe-Yuncheng Basin, tectonic stress field