Abstract: This paper deals with the results of the tentative studies on the observation of multiple separation array of geoelectrical resistivity in the earthquake monitoring station of Jiangning District, Nanjian city, Jiangsu Province. The results indicate that during the tentative observation for 8 months from Feb. to Oct. 2006, there were two months′ synchronous descending of apparent resistivities in the 5 seperation arrays since the end of May 2006, with the variations 4%～2%, which could be obviously correlated with the seasonal changes in the statistics, irrigating process in the observation field at the same time. One could not realize, however, what happened inside the medium during the irrigating process, in other words, where and how large the inference of the electrical properties caused by the process could be. The results of the changes of true resistivits with time in terms of the inversion definitely indicate that the variation of the ture resistivity at the different depths shows big difference: one of the top layer with maximum of 6.5％ and the one of bottom layer with only 1% , which clearly indicate the localization and quatitalizition in ture resistivities by the process.The results show a good prospect from image forecast to the physicai prediction in earthquake studies. This paper also deals with some important issues about the method of multipal separation array of geoelectrical resistivity, such as field inspection, the determination of the number of separations, the method for inversion of the temporal changes of geoelectrical resistivity to ture resistivity and the errors in the inversion, and so on.

Key words: Geoelectrical resistivity, Observation of multiple separation, Observation of earthquake precursor, Seismic observatry of Jiangning