中国大陆7级强震前地下流体前兆时空特征  

Spatial-temporal characteristics of precursory anomaly of underground fluid before M_S7.0 strong earthquakes in China's continent

作　　者：晏锐[1] 黄辅琼[1] 顾瑾平[1] 

机构地区：[1]中国地震局分析预报中心,北京100036

出　　处：《地震》2004年第1期126-131,共6页Earthquake

基　　金：十五"国家科技攻关项目(15 01 05 06);中国地震局分析预报中心地震应急研究专题联合资助

摘　　要：对中国大陆1969年以来11次7级强震前地下流体前兆观测资料分阶段进行统计分析,并选用雷达图描述了中国大陆7级强震前地下流体前兆异常的时空特征,认为其特征主要表现在:异常出现时间上的阶段性与不均匀性,中长期趋势性异常分散,短临异常相对集中,且各占总异常比例的50%左右;震前异常集中在一定的范围内,并沿活动断裂呈现出一定的集中性;中长期趋势异常较早出现在震源区附近,并呈现出由震源区向外围扩散-收缩-扩散-收缩的过程,特别是进入短临阶段后,异常向震源区收缩的趋势更为明显;在震源区(或在距震源较近的范围内)异常所占的比例大,远离震源区所占比例小,且有由震源区向外围逐渐减小的趋势。Precursory data of underground fluid before 11 M_S7.0 strong earthquakes since 1969 in China′s continent were analyzed in this article. Spatial-temporal characteristics of precursory anomaly of underground fluid before M_S7.0 strong earthquakes were described by using radar and statistical diagram. The result indicates that: ① The anomalies show periodical characteristics and ununiformity in time. The mid-long-term anomalies are dispersing, short-term and impending anomalies are relatively concentrated, each anomaly roughly accounts for 50%. ② The anomalies are concentrated in a certain area and distributed along the active faults. ③ The mid-long-term anomalies appear around the earthquake source region in the earliest stage and show the process of diffusion-concentration-diffusion-concentration, and especially when enter the short-impending stage this concentrating trend becomes more apparent. ④ The percentage of the anomalies in the earthquake source region is larger than that far from the earthquake source region. That is to say: There is a trend that the percentage of the anomalies gets more and more small when the distance is farther from the earthquake source region.

关 键 词：地下流体 前兆异常 震源 雷达图 中国大陆 

分 类 号：P315.723[天文地球—地震学]