新丰江水库地震序列的分段研究

Statistic Characteristics of Xinfengjiang Reservoir Earthquake Sequence

从新丰江水库地震序列分段、地震序列参数统计、地震序列分段与库水位关系等方面探讨新丰江地区的地震特征。结果表明:①水库地震全序列低b值(≤0.9)时段与大区域地震活动的增强存在一定的相关性,余震活动在一定程度上具有华南地区地震活动"窗口"的作用。②水库地震晚期余震释放阶段55个ML≥3.5级地震分序列研究显示,1975年以来的各分序列b值明显低于之前,平均值仅为0.66;分序列类型60%以上属于主余型;78%的分序列最大余震发生在主震后2天内,94%发生在主震后10天内。③1964年5.3级强余震后该区地震活动的增强与库水位的上升没有明显的线性关系,且晚期余震释放阶段ML≥4.0级地震73%发生在库水位下降或由下降转为平稳波动的过程中,库水卸载阶段的地震活动更值得关注。

The seismic activity characteristics of Xinfengjiang reservoir earthquake sequence and the relationship between them and the water level changes of the Xinfengjiang reservoir are studied in this paper. The result shows that the low b value period of the earthquake sequence is related to the enhancing of regional seismic activity and to some extent, the earthquake sequence can be seen as a seismic activity .window of Southern China. Studies of 55 earthquake subsequences with main shock of ML≥3.5 indicate that the b value of the subsequence after 1975 are distinctively lower than that of the before, 60 percents of the earthquake subsequences belongs to mainshock-aftershock type, the biggest aftershocks of 78 percents of the earthquake subsequences occur with 2 days after the main shock. There is no distinctive linear relation between the enhancing of seismic activity and water level rising of Xinfengjiang reservoir, instead, 73 percents of the ML≥4.0 earthquakes occurs during the unloading period of Xinfengjiang reservoir.