小浪底水库诱发地震监测及研究

Monitoring and Research on Xiaolangdi Reservoir Induced Earthquakes

利用2009年小浪底地震台网数字化改造后记录到的2009—2011年水库周围20km范围内发生的地震，分析其时空分布特征以及其中61次地震的震源机制解。结果表明，小浪底水库存在诱发地震活动，以弱震和微震为主，最大ML2．8。地震集中分布在2个丛集区，分别与库区的石井河断层、塔底断层有关。库区地震的张应力轴与构造背景最大主压应力轴方向基本一致，倾角30。左右，表明这些地震是在受到一定的相对直立压应力作用下发生的，可能与水库蓄水后库水载荷的长期作用有关。

In this paper, using earthquakes occurring in a range of 20 km around Xiaolangdi reser- voir from 2009 to 201, which were recorded after the digital transformation of Xiaolangdi seismic network at the end of 2009, we analyzed their spatial and temporal distributions and the focal mechanism solutions of 61 earthquake s among them. The results show that there are induced earthquakes in the Xiaolangdi reservoir in which weak shocks and micro earthquakes of largest ML = 2.8 predominate. The earthquakes are concentrated in two cluster regions, which are related to Shijinghe--fault and Tadi--fault respectively. The tensile stress axis of reservoir-induced earthquakes is basically consistent with that of maximum principal stress of tectonic setting; the dip angle is no longer horizontal, but about 30 °. It shows that these earthquakes occur under the action of certain relatively vertical stress, which may be related to the long-term effect of reser- voir water after the storage.