采用双差定位方法对紫坪铺水库库区12个地震台站2009年记录的857个地震进行了重新定位,获得了815个地震的震源位置。定位结果显示库区有3个地震相对集中区域,在各个集中区域地震震源深度的分布特征各不相同。与已有的汶川8.0级地震前库区地震精定位的研究结果相比较,汶川8.0级地震后库区地震相对集中区域的位置关系发生了明显变化。

    815 aftershocks of Wenchuan earthquake recorded by 12 seismic stations in 2009 were relocated using the double difference algorithm to analyze the seismic activity of the Zipingpu reservoir.Relocation results show that the epicenters of aftershocks concentrate relatively in three regions.Focal depth distribution characters of different concentration regions take on obvious difference.This means earthquakes in different concentration regions may have different causes.Compared with relocations of earthquakes taking place before the Wenchuan earthquake done by other researchers,locations of the seismic concentration regions in the reservoir area changed noticeably after the Wenchuan earthquake.These variations are related with the stress adjustment of local part in the reservoir area and may also be related with the diffusion depth and range of increased pore pressure caused by rock failure in the course of Wenchuan earthquake.