中文摘要：

利用小湾水库地震台网连续、完整的地震波资料，计算小湾水库蓄水前、后各1年地震密集区域的小震波速比变化，并分析3级地震震前波速比的显著异常变化特征。结果表明：小湾库区澜沧江段的昌宁、凤庆，黑惠江库区的巍山牛街一带为震群丛集区，且库尾凤庆区域平均波速比低于中段的昌宁区，空间上呈非均匀分布。水库蓄水仅对凤庆区的地下介质有一定的影响，蓄水前后3级地震震前波速比均呈显著低值异常，2009年8月6日凤庆3．5级地震为蓄水后的最大地震，初步判定为水库诱发的构造地震或构造型水库诱发地震。

英文摘要：

Using continuous and complete data of small earthquakes recorded by Xiaowan Reservoir Seismic Network, we calculate the variation of seismic wave velocity ratio for one year before and after water storage of Xiaowan Reservoir in earthquake cluster area, and analyze significant anomaly of wave velocity ratio before M3.0 earth- quakes. The results indicate that earthquake swarm area distributes on Changning and Fengqing Counties of Lan- cang River Fault in Xiaowan Reservoir and Niujie Township in Weishan County in Heihuijiang Reservoir. The wave velocity ratio of Fengqing area in back reservoir is lower than that of Changning area in the middle of the reservoir, and it distributes non-uniform in space. The water storage of reservoir has certain influence on the un- derground medium in Fengqing area. The wave velocity ratio before M3.0 earthquakes appears lower value a- nomaly before water storage. An Fengqing M3.5 earthquake occurred on Aug. 6 in 2009, which is the biggest earthquake in Xiaowan Reservoir after water storage, and induced to be the tectonic earthquake induced by reser- voir or tectonic reservoir-induced earthquake.