华北地区第四活动期两次地震活动过程的相似性研究

A study on similarity between the activity process of two earthquakes during the fourth active period in North China region

着重分析研究华北地区第四活动期以来M_S≥5.0地震时空分布特征。结果表明,该地区第四活动期从1820年至1976年期间,地震活动出现了前后两次基本相似的强弱起伏活动过程,分别历时69年和66年。前后两个活动过程不但时序结构类似,进程一致,且空间演化格局相似,都是先从华北地区的中南部开始,再迁移至东北部辽东半岛及附近海域,最终在华北地区北部集中出现一系列强震活动,而完成整个活动过程。进一步分析表明,前后两活动过程的第一阶段6级以上强震,在空间分布上除南黄海地区外,基本上互不重复。这一现象的发现,有助于该地区今后地震活动主体区域的分析判断。

This article focuses on research the characteristics of spatial distribution for Ms 5.0 earthquake since the fourth active period in North China. The results showed that the seis- micity since fourth activity period in the region occurred two basically similar processes pre and post of the fluctuation between strong and weak during the seismic activity process from 1820 to 1976 lasted for 69 years and 66 years, respectively. The two activity processes pre and post are similar not only in time sequence structure, developing process, but also in special evolution pattern. The both started at central south ot the North China and then moved to the north-eastern part of the Liaodong Peninsula and adjacent sea area and completed the activities with a series of earthquake activities in the northern part of North China ultimate- ly. Further analysis showed that the first period of the two events pre-and post-process more than six strong earthquakes were not essentially repeat each other expect the spatial distribu- tion of the Southern Yellow Sea region. The discovery for this phenomenon will be helpful for the analysis on the main seismic activity area in this region in the future.