Abstract: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.
