Abstract: Entropy shows the systematic microdistributed chaotic degree in the statistics, and it is the mensuration of systematic disordered degree.The higher the entropy is, the higher the systematic disordered degree is,and the system is comparatively uniform.The lower the entropy is, the higher the systematic ordered degree, and the systematic inhomogeneity is high.A seismic preparation process is a process from disordered state to ordered. The variational characteristics of magnitude entropy are different in a seismic preparation process.Bassd on the variational characteristics of magnitude entropy before earthquakes, the seismic information can be extracted.Therefore the occurrence time interval of future earthqukes can be estimated.
The author, basing on the maximum entropy principle, derived the magnitude entropy formula of continuous random variable, and calculated the magnitude entropy of M_l ≥ 2.0 earthquakes occurred in Xinding basin in 1986-1991.The calculated results indicated that the magnitude entropy showed a low value anomaly before the M 6. 1 and 5.7 earthquakes and the earthquakes occurred in the recovery process of magnitude entropy.Therefore the low value anomaly of manitude entropy is an important characteristic before earthquakes.