The spatio-temporal distribution of delay time of S-wave splitting is analyzed based on 260 shear wave time-delay data from local earthquakes in Tengchong area, Yunnan Province. The result shows that the changes in delay time of S-wave splitting are related to the magnitude of three moderate and small earthquake swarms, and delay time of S-wave splitting changes synchronously with the occurrence of the main shock and larger aftershocks in the earthquake swarm which carries the information of stress change during the earthquake swarm, provided that the locations of all earthquakes in the same earthquake swarm are concentrated, thus excluding the influence of differences in propagation path length and spatial azimuth of seismic ray path on delay time of S-wave splitting. Different from most cases in the past, the magnitude of the earthquake swarm in this work is relatively small, with the maximum magnitude ranging from M3.2 to M5.2. At the same time, the distances between the earthquake swarms and the stations are relatively large, generally greater than 30 km, and the largest reaches about 70 km. The information of stress changes during moderate and small earthquakes has been obtained by analyzing delay time of S-wave splitting from distant stations, which has great implications for the wider use of distant small earthquakes to monitor regional stress changes.

基于云南腾冲强震区8个台站观测得到的260条地方震横波分裂数据, 分析快慢横波到时差在时间和空间上的分布特征。结果表明, 横波到时差的变化与观测时窗内3个中小震群的震级有关联, 多个台站的横波到时差随各震群中的较大地震同步变化, 这些横波到时差数据携带了震群发生过程中应力场变化的信息, 前提是各震群中地震发生的空间位置集中, 排除了地震射线传播路径长度和空间方位的差异对横波到时差的影响。与以往大多数情况不同, 3个震群的震级较小, 最大震级在M3.2至M5.2之间, 同时震群的震源距普遍大于30 km, 最大达到70 km左右, 实现通过较远中小震群横波到时差获取震群发生过程中应力变化信息的目标, 对更广泛地利用远距离小震监测区域应力变化有积极意义。