中国大陆地震活跃期及平静期判断的新方法与应用

A new approach to determine the active and quiet period of earthquakes in mainland of China and its application

基于小波变换方法,提出了刻画地震活动周期的指标—周期系数,该系数为描述地震活动周期显著程度的一种量度。应用该方法对中国大陆地区1890～2002年22年左右与10年左右周期(活跃期与平静期组成一个周期)内地震活动周期系数的变化过程进行了分析,结果表明,中国大陆地区的地震活跃期及7.5级以上地震的发生时段处于22年周期系数曲线的下降过程中,而平静期则与周期系数曲线的上升过程相对应。10年左右的周期系数将活跃期与平静期进行了大致分离,从而为地震活跃期的开始与结束的判断提供了一种全新的研究思路与方法。研究表明,中国大陆已处于20世纪以来的"第5活跃期"的尾声。

an index called cycle coefficient, which is a measurement of seismicity, is proposed with the method of wavelet transformation. Based on the method, the variation of the coefficient with 22 years cycle and 10 years cycle from 1890 to 2002 in the mainland of China is analyzed. The results show that the seismic active period and the occurrence of M≥7.5 earthquakes were mainly at the descending segment of the coefficient with 22 years cycle, whereas, the quiet period was at the ascending segment. The coefficient with 10 years cycle can separate the active period from quiet period, which presents a new approach for the judgment of seismic active period. The study shows that the mainland of China has approached to the end of the fifth active period from the 20th century.