长河坝水库蓄水前库区地震精确定位

Accurate Location of Earthquakes before the Water Storage of Changheba Reservoir

摘要:

利用水库地震台网监测数据，对大渡河流域梯级电站中的长河坝水电站蓄水前地震活动进行精确定位，以获得水库蓄水前库区附近地震活动准确位置并对其时空特征进行分析研究。利用波形互相关技术并结合部分地震震相观测报告，采用双差定位方法得到444次地震的精确定位结果，其中大坝附近分布三个高度集中的地震丛集，再通过时间分布分析和卫星影像分析可明确判断其为水库建设期采石爆破事件；水库大坝上游的蓄水区域附近没有地震丛集分布现象，而主要的地震丛集分布于大坝西南至鲜水河断裂带之间，通过利用地震进行断层拟合的方法，给出该地震集中分布区7条小型断裂的产状特征。

Abstract:

Based on the monitoring data of reservoir earthquake observation network, the accurate location of seismic activity before the water storage of Changheba reservoir is presented in this paper, and the space-time distribution characteristics of the earthquakes are analyzed. Using the waveform cross-correlation technique and the phase observation reports of some earthquakes, the accurate location results of 444 earthquakes are obtained using the double-difference location method. The results of time distribution analysis and satellite image analysis clearly show that three highly concentrated seismic clusters distributed near the dam are the quarry blasting events during the reservoir construction; there is no seismic cluster distribution near the water storage area in the upper reaches of the reservoir dam, and the main earthquake clusters are distributed from the southwest of the dam to the Xianshuihe fault zone. In addition, the occurrence features of seven small faults in the earthquake concentrated area are given.