摘要:
本文考察了我国华北及西南 M≥7地震的余震序列, 在M—logt 图上余震活动呈现有交替的高潮期和低潮期;称为准周期性.取高潮期中极大余震发生时间 tn 与周期函数 S(t)=sin[(2πt)/T(t)+(π/2)]的峰值依次拟合, 求得各峰值时的周期 Tn, 各余震序列的结果一致表明 logT=loga+qlogt 的线性关系存在, 即 T=atq.并讨论了 T 随 t 的幂函数增加主要是由于荷载率$ \dot{P}$ 随时间幂函数减小所致.外推 S(t), 可用下一个峰值对应的 t 预测下一个强余震的发震时间.本文还讨论了相邻两强余震的时间间隔与强余震震级的关系.
Abstract:
In this paper, the aftershocks sequences of large earthquakes, M≥7, occurred in South-west and North China indicate alternatively high and low seismic activity on the M-log t diagrams, giving rise to the notion of pseudo-periodicity. By fitting the times of occurrence, tn, of the strongest aftershock of each interval of high seismic activity of an aftershock sequence with the peak values of the periodic function S(t)=sin[(2πt)/T(t)+(π/2)] of period T(t), we found that the linear relation log T=loga+qlogt holds, which means T(t)=atq. It is proposed that the increase of T with t according to a power function is mainly due to the fact that the loading rate $ \dot{P}$ decreases with time in accordance to a power function.By exatrapolation we cam predict the time of occurrence of the next strong aftershock by the next peak value of S(t). The relation between the time interval of two neighbouring strong aftershocks and their magnitudes has also been discussed.
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