In recent years,small and moderate earthquakes have occurred frequently around Gaoling county,making it a high-incidence area in the Weihe Basin. In order to understand the seismogenic structure and seismogenic background of the seismic area,this paper uses the VELEST and typoDD programs to relocate 235 earthquakes of recent years in the area. By re-picking the seismic phases,GPAT method is applied to calculate 26 focal mechanism solutions of the earthquakes with ML≥2.0. The precision positioning results of small earthquakes indicate that the earthquakes in this area are basically distributed above 15 km,and the vertical profile shows a northward shovel-like fault. Based on the distribution of earthquakes,the scale and activity of faults,and the location of the extreme earthquake zone,this paper considers the seismogenic fault of the Gaoling earthquake group to be the Jingyang-Weinan fault. The calculation results of the focal mechanism of small earthquakes show that the area is dominated by horizontal extension of NNW and tendency of compression in NW direction. The dominant direction of the comprehensive slip angle indicates that the seismogenic fault is dominated by normal fault activity and left-lateral strike-slip. GPS data show that the stress in the study area has a complex four-quadrant distribution,and the Gaoling seismic swarm is in the center of the four quadrants. The article speculates that it is this complex stress background that led to the activity of the Gaoling seismic swarm.
维普
万方数据
