地震前地电阻率的异常变化

本文从我国十几年来观测到的地电阻率前兆现象以及自然条件下岩(土)层受压实验结果,提出了地震前地电阻率异常的四种表现特征:异常的形态(上升、下降或反覆的变化)与台站处的地下受力状态有关;异常有方向性;各异常量(时间、幅度)随震级的加大,震中距的缩短而增加;异常的时、空分布与地震活动的异常(时、空、强弱的分布)一致。并且,强震异常有不可恢复的现象。上述结果均不同程度地得到自然条件下压缩岩(土)层的电阻率变化实验结果所证实。为此提出加强地电阻卒的观测,进一步研究其所表现的分布特性,对提高预测效果会带来益处。

EARTH-RESISTIVITY ANOMALIES BEFORE EARTHQUAKES

Based on the observation for more than ten years,it is pointed out that the following four aspects are manifested by earth-resistivity ano-malies before an earthquake:(1) The form of the anomaly (rise or drop or undulatory variation of earth-resistivity) is connected with the force conditions acting on the medium around the observation site;(2) Aniso-tropy is evidenced by the differences in the anomalies along different di-rections;(3) The amplitude,duration and areal extent of the anomaly increase with the magnitude of the earthquake;(4) When a strong earth-quake is impending,the temporal and spatial distribution of resistivity anomalies are similar to the distribution of small earthquake activity,and the earth-resistivity does not resume its original values after the strong shock.The above phenomena have been verified,though in different degrees,by experiments on the variation of resistivity of beds of rock (or earth) under artificial pressure in situ.It is finally suggested that more extensi-ve observation of earth-resistivity and closer study of its anomalous beh-avior will be beneficial to the improvement of its effectiveness as a mea-ns of earthquake prediction.