根据2008年9月至2013年10月金沙江下游水库地震台网监测资料，分析了蓄水期间水库地震影响区的地震活动和震源机制。向家坝水库蓄水1年多，蓄水后库首区A、B段的地震活动频次和强度都维持在较低水平。蓄水期间地震活动显著增加，集中分布在库区C段，并不是蓄水初期地震活动就增加，与库区2013年6月启动第二阶段蓄水有一定相关性，强度在3级地震活动水平。增加的地震活动位于近南北走向的翼子坝、玛瑙断裂的中段。这些局部地段蓄水后发生的地震，其震源的力学机制多为倾滑或正断型，分析认为部分地震为水库诱发岩溶或塌陷型地震，多数仍属构造地震。本文结果为水库诱发地震的研究提供了资料和震例。

In this paper，seismicity and focal mechanism of the reservoir area after the impoundment are studied by using the data of seismic network of Jinsha River low reaches． In the segments A and B of the reservoir head region seismic activity was staying with low frequency and strength in more than one year since the impoundment． While a significant increase of seismicity in segment C had the largest earthquake with M3.0，which was correlating with the second stage impounding but not the initial impoundment period． The region of seismicity increase is near the Yiziba fault and the middle segment of the Manao fault． Most of earthquakes in these regions are reverse and normal rupture according to focal mechanisms，in which tectonic earthquake takes a large proportion while the rest are reservoir induced and Karst collapse． The result will provide detailed information and example for future reservoir induced earthquake study and forecast．

金沙江下游梯级水电站水库地震监测系统建设与运行项目( JS(06)001)资助