强震前后震级分布偏离度时序特征的初步分析

PRELIMINARY ANALYSIS ON THE SEQUENCE CHARACTERISTICS OF MAGNITUDE DISTRIBUTION DEVIATION ROUND THE STRONG EARTHQUAKE

以川滇地区和青藏块体北部地区１９８０年以来的地震目录为依据，分析了在稳健估计理论基础上引出的震级分布偏离度（ξ值）随时间变化的特征。结果表明，强震前ξ值表现为低值状态（有序的自组织临界阶段），震后转变为高值（无序的混沌态），构成强震孕育发生的自组织过程；同时，不同地区地壳构造不同，强震自组织性质也有所差异。ξ值可望作为地震中期预测的一种判别指标。

In this paper, we analysed the time characteristics of magnitude distribution deviation (value of ξ) deduced from the robust estimation theory by use of the earthquake catalogus in Yunnan -Sichuan region and north region of Qinghai-Tibet plateau since 1980. The results showed that the valtle of ξ was small before the strong shock and would rise after the strong shock. It is said that the strong earthquake is one self-organization process and the characteristics of the self-organization would depend on the crustal structure. The valueof ξ could be seen as one index of mid-term prediction of strong earthquake.