大渡河瀑布沟水电站水库地震活动特征分析

Analysis on Seismic Activity Characteristics of the Reservoir in Pubugou Hydropower Station of Dadu River

大渡河瀑布沟水电站水库是大渡河流域典型的高山峡谷型高坝大库,大坝处于相对稳定的瓦山断块,水库库尾则位于龙门山断裂带、鲜水河断裂带、安宁河断裂带的交汇处,地震活动相对强烈,因此,为保证工程及周边地区社会生产生活安全,掌握水库蓄水前后地震活动情况,建立了一套完整的水库诱发地震监测系统,对该区域水库地震活动进行及时准确的监测。通过对近十年的地震观测资料进行统计,分析地震活动特征,总体上水库蓄水后库区附近地震活动水平较低,以微震和小震为主,震级较小,地震频度与水库水位升降无关,水库蓄水后没有造成明显的水库诱发地震情况,为水库地震监测评价和工程安全稳定运行提供了有用的科学依据。

Dadu River Pubugou Hydropower Station is a typical alpine canyon-type hydropower project with high dam and large reservoir in the Dadu River Basin.The dam is situated on relatively stable Washan fault block,and the tail of reservoir is located at the interchange of the Longmenshan fault zone,Xianshuihe fault zone and Anning River fault zone,where seismic activity is relatively strong.Therefore,in order to ensure the safety of production and life in the project and the surrounding areas,and to monitor the seismic activity before and after the reservoir is impounded,a complete reservoir-induced earthquake monitoring system has been established to timely monitor seismic activities in the reservoir.This paper analyzes the characteristics of seismic activity based on the statistics of seismic observation data in the past ten years.Generally speaking,the seismic activity level near the reservoir area is relatively low after the reservoir is impounded,mainly microseisms and small earthquakes,with small magnitudes.There is no correlation between the earthquake frequency and the rise and fall of the reservoir water level,and the impoundment of the reservoir does not cause obvious reservoir-induced seismic activity,which provides technical support for the seismic monitoring and evaluation of the reservoir and the safe and stable operation of the project.