Three typical stages in the resistivity anomalies were observed in the neighbourhood of the epicentres before a number of great and medium ear-thquakes in China.Those anomalies of different stages were remarkedly different from each other in their forms and laus.This paper systematically deals with the resistivity observations of the short-term and imminent-term before earthquakes,and presents their characteristics at this stage.
The relationship between resistivity anomalies and the preparation pro-cess of earthquakes is also discussed preliminarily in this paper.Some con-ditions on which the short-term and imminent term anomalies might be observed more outstandingly and validly are presented.Those conditions are as follows:the structure of underground medium of an observatory,of possible,should be adapted to ρ₂/ρ₁ << 1,and the smaller the amplitude of so-called "annual change" in the resistivity observation is,the better it will be.