中国大陆7级地震活动状态分析

在前人研究中国大陆地震活动的时间非平稳性认识的基础上, 将中国大陆7级以上地震活动状态划分为三类, 分别为少发时段(平静期)、 增多时段、 丛发时段(活跃期), 将这三类时段简称为: Ⅰ类时段、 Ⅱ类时段和Ⅲ类时段。 并利用显著性检验对相应划分结果进行了初步分析, 认为中国大陆可能以Ⅱ类时段为其基本状态, Ⅲ类时段和Ⅰ类时段均是在Ⅱ类时段状态上的上下偏离; 中国大陆自1901年以来的前后50余年的强震活动基本状态并没有发生显著改变, 今后一段时期内的7级以上强震活动可能仍将重复20世纪的活动规律; 1901年以来的百年资料显示, 每一个Ⅲ类时段前都存在一个Ⅱ类时段, 强震活动增强需要一个过程, 没有Ⅰ类时段直接进入Ⅲ类时段的先例; 2008年3月21日新疆于田7.3级地震的发生, 可能意味着中国大陆已进入Ⅱ类时段。

State analysis on M7 earthquake activity in China continent

Based on researches of unsteady state of earthquakes in China continent, this research divided the status of activity of M>7 earthquakes in China continent into three types, they are intermittent (quiet) phase, sporadically occurring phase, frequently occurring (active) phase, respectively. Then this research analyzed the different types by means of the significance test and concluded that the basic status of earthquake activity in China continent may be sporadically occurring phase; the intermittent or frequently occurring status may deviate from the sporadically occurring status. As for earthquake activity of China continent during the last century, there is no obvious difference of the earthquake activity during the former fifty years and the latter fifty years. The characteristics of future earthquake activity may be as the same as the characteristics of earthquake activity during the last century. Based on the data since 1901, there always was a sporadically occurring phase before a frequently occurring phase. And there was not any case that earthquakes frequently occurred after intermittent phase. So Yutian 7.3 earthquake, on March 21, 2008, may be the symbol of the beginning of new sporadically occurring phase of earthquake activity in China continent.