【摘要】 研究了河北张北等３次６级地震前后地电异常的变化及特征。结果表明，６级地震的地电前兆能显示出０．５ａ左右的趋势异常变化，但台项少，强度弱，分布零散，远不及７级强震前的异常显著。发现个别地震前地电正常年变化形态发生了明显变化，完全破坏了原年变规律，出现了可辨认的异常变化。认为用地电方法在目前实现中强地震的准确预报是比较困难的更多还原

【Abstract】 The research results for the ground resistivity variation and its characters before and after the 3 earthquakes with M6 0 at Zhangbei of Hebei showed that the earthquake precursors of ground resistivity before M6 0 erthquake can show tendency anomalous variation about 0 5 a,it is not as good as the M7 0 strong earthquake.The results showed that the annual variation shape of the ground resistivity before individual earthquake changed obviously,it left the original annual variation law,the distinguishable anomalous variation occurred.The author suggested that the exact mediumstrong earthquake pridiction by the ground resistivity method is difficult to make at present.更多还原