关键词: 地震活动性，维西-乔后断层，分支断层

Abstract: Based on the seismic data from temporary stations and regional stations in the northwestern area of Yunnan, we use waveform correlation methods to perform high-resolution detection and high-precision location on continuous waveforms recorded from February 25, 2018 to July 31, 2019, and the seismicity characteristics of the Weixi-Qiaohou fault in the northern section of the Red River fault zone are analyzed. Studies have shown that, except for some special fault locations (such as terraces, intersections, etc.), currently the Weixi-Qiaohou fault has weak seismic activity, but there may be a hidden steep-dip right-lateral strike-slip fault along the west side of the fault. Small earthquakes on the fault are active. Statistical parameters, such as seismic frequency, energy release rate and b-value, indicate that the seismic activity in the Weixi-Qiaohou fault and its surrounding areas is relatively stable, and the regional stress enhancement is not obvious. The b-value is relatively high in most areas, and low b-value areas are mainly distributed in some special fault locations (such as terraces, intersections, etc.), but the scale is generally small. The statistical results of the ETAS model show that more than 40% of seismic activity may be affected by external factors such as deep fluid disturbance and remote strong earthquake triggers. Therefore, we believe that the Weixi-Qiaohou fault is currently not active, but the hidden branch faults on the west side clustered with small earthquakes have a tendency to increase. We need to comprehensively pay attention to the occurrence of moderate-strong earthquakes on the main fault and these branch faults.

Key words: Seismicity, Weixi-Qiaohou Fault, Branch Fault