华北地区地震分布多标度分形特征的初步研究

A PRELIMINARY STUDY ON THE MULTI-FRACTAL OF EARTHQUAKE DISTRIBUTION IN NORTH CHINA

摘要:

依据"固定质量法"的定义及原理,本文给出了一种判断地震空间分布分形结构及计算D_q的方法。利用该方法对华北地区地震的空间分布特征进行了初步研究。结果表明,在满足一定的统计条件下,不同区域范围内、不同时间段的地震分布均具有分形结构。围绕海城、唐山大震区分别选择4个大小不同的区域,分不同时段计算其D_q-q谱。结果表明,强震前后其形态无显著变化。强震前在较大的区域范围内,D₀值有降低的趋势,震后回升;在震源区周围较小区域内,D₀的变化相反;而有的区域强震前后D₀值没有变化。

Abstract:

According to. the definition and,,principle of "fixed mass method", a numerical method is given in this paper, which can be used to judge, the earthquake space-distribution fractal and calculate its dimension. Using this method, the features of earthquake, distribution in North China is studied. The results. Show that satisfying certain statistic conditions, the earthquake distribution belongs fractal in different areas and periods. Selecting different areas and periods in the epicentral areas of the Tangshan and Haicheng earthquakes, the D_q-q spectra are calculated. The,results show that there is no marked change for the D_q versus q curves before and after the strong earthquakes. The results also show that for large areas, the D₀ value has reducing trend before strong earthquakes, and increase after the events; it is opposite for small areas; and for some areas, the D₀ seldom changes before and after strong events.