2008年西藏4次M_S6.0以上地震前拉萨地电场异常信号特征  

Abnormal Characterisrics of Geoelectric Field at Lhasa Station before 4 M_S6.0 Earthquakes of 2008 in Tibet

作　　者：马钦忠[1] 唐宇雄[2] 张永仙[3] 

机构地区：[1]上海市地震局,上海201203 [2]四川省地震局,四川成都610041 [3]中国地震台网中心,北京100045

出　　处：《地震》2011年第1期86-97,共12页Earthquake

基　　金：天地一体化地震预测示范应用研究项目资助

摘　　要：2008年西藏发生了4次MS6.0以上地震,即1月9日改则MS6.9地震、8月25日仲巴MS6.8地震、9月25日仲巴县MS6.0地震、10月6日当雄MS6.6地震。通过检查和分析拉萨台观测资料,发现在这四次中强地震前都记录到了明显的地电场异常信号。对于远震,震级和最大异常幅度与震中距乘积的对数存在着线性关系;在震前异常电信号出现的时间段内,异常地电场极化矢量方向基本上呈现出偏离正常线性极化方向。由于拉萨台的周边没有较大的工业设施,观测环境良好,因此这些异常信号的可信度比较高。本文通过总结,为识别地震电信号提供了很有意义的震例。In 2008,four MS6.0 earthquakes occurred in Tibet,i.e.the Jan.9 Gaize MS6.9,the Aug.25 Zhongba MS6.8,the Sep.Zhongba county MS6.0 and the Oct.6 Dangxiong MS6.6 earthquakes.By examing and analysing data from Lhasa station,we found that there are obvious abnormal geoelectric signals before these four moderate-strong earthquakes.For far earthquakes,the earthquake magnitude is linearly related to the logorithm of the product of abnormaly and epicentral distance,and in the time period of anomaly before earthquakes,the polarized vectors deviate from the normal directions.It was found that these anormalou signals have a high degree of reliability because the Lhasa sation has a better observing environment without large industrial installation nearby.

关 键 词：地震 地电场异常 多级距观测 拉萨台 

分 类 号：P315.7[天文地球—地震学]