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Title:: Double-difference Relocation of Earthquakes in Longtan Reservoir Combined with Waveform Cross-Correlation Technique

Author(s):: YAN Chunheng; ZHOU Bin; GUO Peilan; SUN Xuejun; WEN Xiang; (Earthquake Bureau of the Guangxi Zhuang Autonomous Region, Nanning 530022, Guangxi, China)

Keywords:: reservoir-induced seismicity; precise relocation of earthquake; double-difference location algorithm; waveform cross-correlation; Longtan Reservoir

摘要:: 利用结合波形互相关技术的双差定位法对龙滩库区2006年9月30日至2013年5月26日发生的3 682次地震进行精定位,获得了精度更高的定位结果,平均理论误差小于10 m。精定位结果显示:蓄水后龙滩库区中小地震活动呈现明显的丛集性,主要集中在罗妥、八茂、拉浪、坝首、布柳河以及库区下游的天峨县城6个区域,每个地震丛的分布范围在10 km内,优势深度为4～9 km,优势展布方向与穿过该地震丛的主要断裂带的走向或倾向一致,表明库区地震活动基本分布在河流及断层附近10 km范围内,表现出水库诱发地震活动典型的“双十”特征。研究成果可为龙滩水库续建工程诱发地震的预测与地震安全性评价提供依据。

Abstract:: Using the double-difference location algorithm combined with waveform cross-correlation technique, we relocated 3 682 earthquakes occurred around Longtan Reservoir from Sep.30, 2006 to May.26, 2013. The relocating results are more precise than that of network catalogue, and its logically mean error is less than 10 m. The precise location results show that, the distribution of mid-small earthquakes shows obvious cluster in the 6 regions of Luotuo, Bamao, Lalang, Bashou, Buliuhe and Tian'e County after impounding. The distribution range of each earthquakes cluster is no more than 10 km and the focal depths dominantly distributed in 4～9 km, and its advantageous spread direction is consistent to the strike or trend of main faults which pass through the earthquakes cluster. These results indicate that the earthquakes in the reservoir basically distribute in the range of less than 10 km around the rivers and faults, which shows the typical “double ten” characteristics of reservoir-induced seismic activity. The obtained research results are useful to predict earthquake induced by Longtan Reservoir reconstruction project and could provide the basis for seismic safety assessment.