基于空间点模式分析的地震空间分布集中趋势特性

Study of the Central Tendency of Earthquake Based on Spatial Point Pattern Analysis

地震序列的时空相关性在地震运动趋势分析中发挥着基础性的作用。时空相关性的一个最直接作用是一个强震发生以后促使一定空间区域甚至全球范围的地震群的发生。该文借助现有空间点模式分析方法,通过均数中心,加权均数中心,几何均数中心和调和均数中心函数,尝试探索一种空间相关性方法来描述强震与其震后临近的非强震之间的相关性与趋势特性。该文研究工作中,相关性和趋势特性的物理基础是在地理学第一定律的背景下讨论的——任何事物之间时空相关。均数中心函数方法应用于中国境内地区。结果显示,中国境内强震震后的余震群并非以强震为均数中心均匀分布,其均数中心与强震空间位置存在明显偏移特征。

Correlations in space and time among approaching earthquakes play a fundamental role in earthquake motion trend analysis. One direct effect of the correlations is a promotion of earthquake swarms occurred in a certain region even worldwide after a strong earthquake. The variability of the random variable over space in correlations may occur in earthquake swarms after strong earthquakes. Using the classical analysis method of spatial point pattern, it is possible to introduce a measure of spatial correlation and trend between strong earthquakes and the aftershocks, through the function of mean center（MC）, weighted mean center（WMC）, geometric mean center（GMC） and harmonic mean center（HMC）. The method of mean center functions is applied to the earthquakes of China. The result shows that in China, aftershock swarms did not evenly spread around the strong earthquakes as the mean center. And there is an obvious migration between the strong earthquakes and the mean centers position of aftershock swarms.