全球强震活动性的某些统计特征

根据阿部胜征新近研究和发表的均匀化全球大地震目录(1897——1980),获得如下几点关于全球强震活动性统计特征的初步认识:(1)本世纪六十年代中期之后,全球活动处于相对平静的阶段;(2)在全球活动高潮时段中b值偏低,大陆地震区的b值偏低;(3)据聚类分析方法研究序列的结果,全球不同的地震区内,存在几十年尺度的强震活动高潮幕和平静幕交替出现的现象;(4)北半球大陆浅源强震活动的空间分布和地球自转速率的变化特征有关。上述特征对估计全球和不同地震区的地震活动趋势可能有参考意义。 

SOME STATISTICAL CHARACTERISTICS OF GLOBAL ACTIVITY OF LARGE EARTHQUAKES

Based on the uniform catalogue of large earthquakes of the earth studied and published by K. Abe, some knowledge about global activity of strong shocks might be obtained. (1) The global seismicity is in a stage of relative quiesence since the late 1960 's. (2) The b-value is lower in continental seismic regions than in other regions (belts); the b-value is lower during the seismically active period than in a quiet one. (3) According to cluster analysis, it may be recongnized that the seismically active and quiet episodes occur alternatively in different seismic regions. (4) There may be some correlation between the distribution of epicenters of large shallow earthquakes in continents of the northern semisphere and the change in velocity of the earth's rotation.The above characteristics might be referential for evaluating the tendency of earthquake occurrence in some seismic regions.