674 small earthquakes occurred from 2016 to 2019 near Xiaojiang Fault Zone, Yunnan are relocated using local dense array data. The focal mechanisms of 222 small earthquakes around are determined by HASH algorithm using P-wave first-motion polarities and S/P amplitude ratios. The tectonic stress field is inversed by MSTASI algorithm. The results indicate that the earthquakes around Xiaojiang Fault Zone are mainly left lateral strike slip, and the direction of principal compressive stress obtained from focal mechanism inversion is NW-SE, which is in good agreement with previous research results and regional GPS observation results. Compared with the north section of Xiaojiang Fault Zone, the horizontal tectonic compressive stress in the middle and south section has been reduced, which might be related with tectonic stress release.

利用云南小江断裂带密集地震台阵的区域地震波形观测资料, 对台阵覆盖区2016—2019年的地震事件进行定位, 获得674个地震的定位结果。通过P波初动极性与S/P振幅比方法(HASH)反演, 确定其中222个小地震的震源机制解, 进而通过MSTASI程序反演小江区域构造应力场。结果表明, 小江断裂带周边地震以左旋走滑为主, 由震源机制反演得到的主压应力方向为NW-SE向, 与前人研究结果以及区域 GPS观测结果有较好的一致性。初步分析显示, 与小江断裂带北段相比, 小江断裂带中南段受到的水平构造压应力略为减缓, 可能与区域构造应力的释放有关。