广东新丰江地区地震研究
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摘要
从水库水位变化与地震活动的关系、地震序列统计、地震活动性等方面探讨了广东新丰江地区的地震特征。地震与水库蓄水变化的研究表明,1965年至今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,并且ML≥4.0级地震65%发生在库水位下降或由下降转为平稳波动的过程中,因此,更应关注水库卸荷阶段的地震活动。对于1970年以来该区记录完整的71次ML3.5级以上地震资料研究显示,主余型、多震型和孤立型地震序列所占比例分别为60%、25%和15%;绝大多数序列最大余震均发生在震后30天内,78%的序列三个月内最大余震发生在震后2天内,94%发生在震后10天内;就主余型序列而言,当主震震级较高时最大余震与主震间时间间隔相对较长,主震震级较低时最大余震与主震间时间间隔相对较短;ML4.0级以上地震活动成丛分布明显。
Study of earthquakes and changes of reservoir water level shows that the enhancement of earthquakes and the raise of reservoir water levels have no obvious linear relation in Xinfengjiang region after 1965.The tempestuousness raise and descent of reservoir water level should be paid more attention to because earthquakes of moderate magnitude may be induced by the load or unload of water in a short time period.Based on 71 earthquakes of ML≥3.5 occurred in Xinfengjiang region from 1970 to 2007,statistical features of the sequences have been studied.For sequence types in Xinfengjiang region,about 60 % belong to the mainshock-aftershock sequences,25 % are the multiple mainshock types and 15 % are the isolated earthquake types.Normally the maximum aftershock occurred within 30 days after the mainshock for most sequences.For about 78 % cases the maximum aftershock occurred within 2 days after the mainshock,and 94 % within 10 days.For the mainshock-aftershock sequences,the time interval from the mainshock to the maximum aftershock tends to be longer when the mainshock is larger,and the interval is shorter when the mainshock is smaller.The reference values given by this study may help the forepart judgment of earthquake sequence types after earthquakes.
Study of earthquakes and changes of reservoir water level shows that the enhancement of earthquakes and the raise of reservoir water levels have no obvious linear relation in Xinfengjiang region after 1965.The tempestuousness raise and descent of reservoir water level should be paid more attention to because earthquakes of moderate magnitude may be induced by the load or unload of water in a short time period.Based on 71 earthquakes of ML≥3.5 occurred in Xinfengjiang region from 1970 to 2007,statistical features of the sequences have been studied.For sequence types in Xinfengjiang region,about 60 % belong to the mainshock-aftershock sequences,25 % are the multiple mainshock types and 15 % are the isolated earthquake types.Normally the maximum aftershock occurred within 30 days after the mainshock for most sequences.For about 78 % cases the maximum aftershock occurred within 2 days after the mainshock,and 94 % within 10 days.For the mainshock-aftershock sequences,the time interval from the mainshock to the maximum aftershock tends to be longer when the mainshock is larger,and the interval is shorter when the mainshock is smaller.The reference values given by this study may help the forepart judgment of earthquake sequence types after earthquakes.
引文
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[2]杨清源,胡毓良,陈献程,等.国内外水库诱发地震目录[J].地震地质,1996,18(4):453-461.
[3]Utsu T.Statistical Features of Seismicity,International Handbook of Earthquake and Engineering Seismology,81A.Elservier,Amsterdam:Academic Press,2002.719-731.
[4]吴开统,焦远碧,吕培苓,等.地震序列概论[M].北京:北京大学出版社,1999.97-114.
[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.
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