华北地区中强地震前的地电阻率异常特征分析

The earth-resistivity anomaly characteristics analysis before the moderate earthquake in North China

用周期综合分析方法对华北地区1985年初～2002年底发生的5级以上地震进行研究。结果表明,华北地区中强地震前地电阻率异常均为负异常,异常时间为中长期时间尺度。地震发生在地电阻率异常曲线的下降、恢复过程中或恢复后。

The earthquakes with magnitude M_S≥5 occurred in North China from 1985~2002 were studied in this paper with method of periodical synthesis analysis.The results indicate that the earth-resistivity anomaly characteristics in North China before the earthquake were all negative.The anomalous duration was long or medium.Earthquake often took place in the decrease,restoring or after restoring of the earth-resistivity curve.