Discussion about correlation of some seismological parameters in medium- and short term earthquake prediction

There are lots of seismological parameters proposed for studying the earthquake prediction by using seismicity pattern. It is very important that whether these parameters are mutually correlated for synthetic earthquake prediction. We make five earthquake catalogues in which the time, location and magnitude of earthquakes are coincident respectively with the even distribution, Poisson distribution, negative exponent distribution and Weibull distribution. Using those catalogues and a natural earthquake catalogue of North China from 1977 to 1988, in which there was no strong earthquake occurred, we compute the b, C, D, Mf and N values and study their mutual correlation in statistics. From the research result and considering the physical mechanism, we conclude that D and N values are obviously correlated, b and Mf values are obviously negatively correlated. Among the rest parameters (excepting one or two), there is not obvious correlation in the random earthquake catalogues, but other parameters are all correlated to a certain degree in North China natural earthquake catalogue. We think that this result should be considered in practice. We also give some suggestion regarding how to use these parameters in earthquake prediction.