新丰江水库地震序列的分段研究
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摘要
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.
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.
引文
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[2]易立新,王广才,李榴芬.水文地质结构与水库诱发地震[J].水文地质工程地质,2004(2),29-32.
[3]魏柏林,冯绚敏,陈定国,等.东南沿海地震活动特征[M].地震出版社,2001,154-162.
[4]杨马陵,叶东华,叶秀薇,等.新丰江水库诱发地震研究报告[R].“新丰江水电站大坝第三轮定检”资料之五.27-35.
[5]蒋海昆,曲延军,李永莉,等.中国大陆中强地震余震序列的部分统计特征[J].地球物理学报,2006,49(4):1110-1117.
[6]周翠英,蒋海昆,周焕鹏,等.华东中强震的构造分类及地震活动图像中、短期异常特征[J].地震,2004,24(4):87-96.
[7]中国地震局.地震现场工作大纲和技术指南[M].北京:地震出版社,1998:25-26.
[8]万永芳,叶东华,陈大庆.广东新丰江地区地震研究[J].华南地震,2008,28(2):59-66.
[9]龚钢延,谢原定.新丰江水库地震区内孔隙流体扩散与原地水力扩散率的研究[J].地震学报,1991,13(3):364-371.
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