Accelerated variation of earth-resistivity as a short-immediate precursor of earthquake

From the viewpoint of geophysics, if you want to study the variations of a physics parameter, you should first research the variations of its amplitude, direction and the rate of chagnes. For the variations of ps which is most important in geoelectricity, a lot of researches are about the amplitude and direction. The following research is mainly about the rate of changes,especially about the sudden change generated by acceleration variations. Rikitake et al. ( 1 9 7 6 ) reported a kind of sudden change that almost occurred at the same time with earthquake. However , this kind of change is difficult to apply in earthquake prediction. People pay attention to the sudden changes which can be used as earthquake precursors. The reasons causing sudden changes can be divided into two types. One is man-made sudden change due to abnormal work of an instrument, line leakage,environmental change, etc. The other is non man-made sudden change and is dependent on the variation of state in the earth medium. The change of stress will be able to change structure of electrical profiling and electric property. The sudden stress drop may cause fast change and made the sudden change. The rock microcrack,acceleration crack and sew up crack can generate sudden change that is caused by fast distribution again of hole liquid. Elevation and subsidence of ground-water may cause the sudden change that is caused by fast variation of electrical thickness in the shallow layer. And once the deep and shallow water containing different salinity are linked each other , i t can also cause the sudden change etc. Now we select all earth-resistivity data of the geoelectric network of Yunnan during the time period from 1979-1987 . The network consists Yuanmou, Tengchong,Chuxiong and Tonghai four geoelectric stations. In the data processing,first of all , we calculate all the daily means of the earth resist ivi ty, then the daily variation rate of the daily relative change of p ,