华北地震同日本地震的相关性

本文对比了1918—1976年发生的中国华北地震和日本列岛及其附近的较大地震,发现二者有比较好的对应关系。一般是,日本海沟先发生7—8级大地震序列,其后日本海西部发生h≥300公里的深源地震,最后我国华北地区发生M≥6的强烈地震。对1918年以来的十四个活动期进行了统计分析,得到复相关系数R=0.82,能够在很高的显著性水平上通过F检验。日本海沟地震约有30年左右的重复期。从1926年至今,日本海沟地震的活动中心向北漂移了3°—4°,与此同时,我国华北地震活动也以相同速率向北迁移。地震活动在时间和强度上的相关性、震中的相关迁移以及震源机制等方面的事实都表明,我国华北强烈地震可能受日本海沟板块俯冲运动的控制,上地幔中可能存在着某种物质流动的通道。

THE CORRELATION OF EARTHQUAKE OCCURRENCE BETWEEN NORTHEASTERN CHINA AND JAPAN

In this paper,major earthquakes which occurred in Northeastern China and Japan and its vicinity during the period from 1918 through 1976 are compared. It is found that there is a good correspondence of earthquake occurrence between the above two regions. Generally,great earthquake series of magnitude 7-8 initially occur along the Japan Trench,then deep-focus earthquakes with depths more than 300 kilometers take place under the west part of the Japan Sea,and finally major shallow earth-quakes of M ≥ 6 appear in Northeastern China. A statistical analysis was made for fourteen active periods since 1918,and a complex correlation coefficient R = 0.82 is obtained which passes the .F-test on a high level of significance. Earthquakes along the Japan Trench have a return period of about 30 years. From 1926 till now,the center of seismic activity along the Japan Trench has drifted northward for 3°-4°. In the interim,the earthquake activity of Northeastern China also drifted northward with the same rate. Various evidences show that the occurrence of major earthqua-kes in Northeastern China are under the control of the down-going movement of the Pacific plate along the Japan Trench,and it seems possible that there exists a chan-nel of material current between the above two regions in the upper mantle.