大同5．5级地震前的电磁前兆信号  

Analysis of the seismo-electromagnetic anomaly before the 5.5magnitude earthquake on 18th October,1989 in Datong,Shanxi Province

作　　者：钱书清[1] 陈智勇[1] 李彦堂 吕智任克新 徐东红[1] 郭勇[1] 姬志勇 

机构地区：[1]国家地震局地球物理研究所,河北省廊坊市地震局,河北省邯郸市地震局

出　　处：《地震地磁观测与研究》1996年第1期54-60,共7页Seismological and Geomagnetic Observation and Research

摘　　要：１９７６年唐山地震以后，由地震引起的电磁信号异常现象开始引起人们的极大关注。我国相继建立了２００多个地震电磁波观测台，并且积累了许多震例资料．同时在国外也发表了一些相关的文章，但大多数文章仅涉及到震前一个台的异常信号或某个频段上的异常信号。１９８９年１０月１８日的山西大同５．５级地震是最近１０年来华北地区最大的中强地震，而且是在３个小时内连续发生了３个５级地震，这也是华北地区从８０年代建立电磁波观测台网以来遇到的第一个最大的中强地震。我们收集了距震中２００—３００ｋｍ范围内，１２个台站震前震后共两个月间的不同频段的观测记录，记录显示出信号幅度由小变大，波形表现为波动、大幅度突跳、趋于平静、平静后发震的电磁信号动态变化的全过程。这次地震前出现的电磁辐射信号的特点是：异常时间长、信号大、频段范围宽（０．０１Ｈｚ—１．６５ＭＨｚ）、异常范围大．因地壳构造的复杂性、介质电性质的非均匀性、不同频率信号传播的多途径性导致了地面上各观测台站所记录到的异常信号出现时间不同步，并且幅度的分布是非线性的．Great attention has been drawn to the Seismo-electromagnetic (SEM) waves after the large Tangshan earthquake in 1976.About 200 stations have been established for observation SEM waves at earthquake risk region in China.We have accumulated many predictive data of SEM waves and earthquake Samiles.Similar articles have been published in foreign country,anomaluos signals at single station or in one frequency band were involved in these reports.One of the most prominent abnormal SEM was recorded before the 5.5magnitude earthquake on 18th,October 1989 in Datong,Shaxi Province,as well as three earthquakes(Ms: 5.5)had occurred continuously in three hours.These earthquakes were the greatest at Huabei area in the near decade.We have collected SEM observationdata at 12 stations within the epicentral distance of 200 300km in different frequency bands for two monthes before earthquake till earthquake occurred.Amplitude of anomalous signals changed from small to bigger,and shape of signals changed from undulation to pulses,then quieted.Earthquake would occurs after some days.There were features of SEM befor middle earthquake:(1) long time of anomaly;(2)larger amplitued:(3)wider radiation extent and (4) wider radiation frequency band.Time of appearing SEM anomaly at different stations and in different frequency bands was not synchronous due to complexity of structure on the earth's crust,conduction of fairly inhomogeneous medium and different propagation of SEM from seismic source.

关 键 词：电磁辐射 前兆信号 地震前兆 地震预报 

分 类 号：P315.7[天文地球—地震学]