Abstract: The spatial ordering of M≥7 earthquake epicenters in North China was studied quantitatively.The pattern of epicenters was identified in terms of simple geometric forms,such as isosceles triangles,equilateral triangles,and parallelograms.Statistics have been performed on the lengths of the sides of isosceles triangles which are considered equilateral.These side lengths are distributed in a range from 240-650 km.The equality of distances between large earthquakes permits us to reexamine the relationship between large earthquake and surface geological structure.It is suggested that the generation of large earthquakes may be more closely related with deep crustal structures,and surface faults are merely their expressions and response to their indirect effects.

Key words: North China, Macroquake, Epicenter, Ordered degree

摘要： 定量研究华北7级以上大地震的震中空间有序性。震中图象可用简单几何形式,如等腰三角形、等边三角形、平行四边形来描述。对于等腰三角形的两边相等的边长进行统计,边长在240～650km范围内。大地震之间的等距使我们重新考虑大地震与地表地质构造的关系。因而提出大地震形成与地壳深处的构造关系较为密切,而地表断裂仅是其间接效应和反映。

关键词: 华北, 大震, 震中, 有序度