全球及中国大陆强震时序活动特征

THE CHARACTERISTICS OF TIME SERIES OF STRONG EARTHQUAKES IN THE WORLD AND CHINA'S MAINLAND

基于强震目录,讨论了全球、中国大陆西部及周边"大三角地区"和中国大陆地区强震活动时序特征。依据8级地震分段活动特征分析认为,20世纪60年代前后全球特大地震活动状态存在显著差异;利用最优分割统计分析认为,自1800年以来"大三角地区"经历了持续时间为100余年的8级地震活动过程;进一步分析认为全球和"大三角"地区强震活动可能具有至少百年尺度的地震"周期",而且具有一定的准同步性。中国大陆地区MS≥7.0浅源地震活动明显受控于"大三角"地区和全球更大空间尺度的地震活动,地震活动时序上表现为十几年和近百年不同时间层次上的活动特征。

Based on strong earthquake catalogue, this paper discussed the activity characteristics of time se- ries of strong earthquakes in the world,western China mainland and its peripheral ＂big triangle＂ seis- mic region, as well as Chinese continent. According to the analysis of the periodic features of global seismicity of MI〉 8 strong events,we find that the global seismicity alternates between phases of dec- ade scale of relatively strong and weak activities, and there are significant differences existing in the activity states of global great earthquakes before and after the 1960s. In addition,statistical analysis with Fisher method has revealed that the ＂big triangular seismic region＂ has experienced the process of M8 earthquake activity with a duration over a hundred years since 1800（ quiescence stage-the tran-cence stage before active-concentrated active stage-adjustment stage after concentrated activity-quies- stage） ; further analysis shows the seismicity of the world and the ＂big triangular seismic re- gion＂ possibly has a period of a hundred-year scale, and has a certain degree of the quasi-synchroniza- tion. The shallow earthquake activity of Ms 1〉 7.0 in China continent is obviously controlled by the seismicity in the big triangular seismic region and by the larger spatial scaled global seismicity. In terms of the time series of these earthquakes,the seismicity shows a decadal or century-scale activity patterns. In the former 50 years of the last century,in the relatively active state of global MS. 5 great earthquakes,the seismicity in the western part of China mainland and its adjacent ＂large triangular seismic region＂ was also active synchronously; however,the quasi-periodic feature of seismicity alter- nating between quiet and active periods of M 〉I 7 earthquakes in China continent was not obvious. While in the latter 50 years of the last century,in the background of MS. 5 seismic quiescence in glob- al and M7 seismic quiescence in the big triangular seismic region,the characteristics of seismic quies- cence and active alternating of M~〉7 earthquakes in the mainland of China was obvious,the seismicity showed a better quasi-periodic feature of activity and quiescence alternatively in decade scale. Conse- quently, not only the temporal sequence of strong earthquakes present an activity feature of a ten-year period and nearly a century period in different time levels,but also the regional strong seismic activity in the China continent obviously is controlled by the strong seismicity of ＂ big triangular seismic re- gion＂ ,even by the global strong seismicity in larger spatial scale. This paper mainly uses the statisti- cal methods to describe the characteristics of time series of strong earthquake activity in different re- gions, and analysis is focused on the temporal and spatial distribution of seismic activity, while, to gain an insight into the tectonic origin and geodynamic implication for these phenomena requires further in- depth study.