龙潭水库诱发地震震源参数分析

摘要

By using the digital seismic wave recording data from the Seismic Network of Longtan Dam, Guangxi Province, the earthquake source parameters is calculated with the method of seismic wave spectral analysis. Our calculation shows that the apparent stress values around Longtan Dam range from 0 to 3.5 Pa and the apparent stress drop caused by an M4.5 Earthquake on 17 July 2007 is 3.07 Pa. The apparent stress drop changes with the power law of the earthquake magnitude. The fitting relation is：σapp=0.0046M^4.34, and R^2 =0.71. The average apparent stress of the dam area is higher than that of northern and western area. The corner frequency has increased with the time since October 2008. The calculation results show that the earthquake magnitude around the dam does not get big and the break length of earthquakes gets smaller and so the apparent stress decrease.%利用广西龙滩水库地震台网记录的数字地震波资料，用波谱分析方法计算了龙滩水库库区ML2．5—4．5级共计95个地震的震源参数。并对震源参数进行分析，结果表明：库区视应力的范围在0-3．5巴之间，2007年7月17日库区最大4．5级地震的视应力最大，为3．07巴。视应力随震级的增大呈幂函数增大趋势，两者的拟合关系为：σapp=0．0046M^4.34，R^2=0．71。水库坝址所在区域（南区）的平均视应力水平相对于北区和西区要高。拐角频率随时间从2008年10月底以来有一个比较显著的上升趋势。说明2008年底以来，库区地震震级在无上升趋势的情况下，地震破裂尺度在减小，区域应力在减小。