强余震活动的持续时间

本文初步分析了1966——1980年间,我国陆内华北和西南川滇地区九次7级以上和十二次6——6.9级浅源地震序列的强余震活动持续时间(△T),以及有关问题。并给出一些经验性结果: (1)这些序列的△T长短差异较大,并和主震震级大小似乎无关。 (2)△T的长短和序列总体的余震频度衰减系数(p)的大小有关。对于p>1的序列,△T1的序列,△T>150天。并且强余震活动终止在频度衰减曲线的拐点时间附近。 规律极其复杂,不免出现例外情况。 

DURATION OF THE SEQUENCE OF STRONG AFTERSHOCKS OF A MAJOR EARTHQUAKE

In this paper, the durations of the sequence of strong aftershocks of 21 shallow major earthquakes, M6.0, occurred in North and Southwest China during 1966-1980 have been discussed, giving some empirical results as follows:(1) The duration △T of such sequences are not the same and they do not seem to be related to the magnitudes of the main shocks.(2) △T's are related to the overall attenuation coefficient (p) of the aftershock frequency of the entire earthquake sequence. For the sequence with p>1, △T150 days and the sequence of strong aftershocks ends at about an inflection point of the attenuation curve of aftershock frequency.There are inevitably exceptions to the empirical relations thus obtained because of the extremely complicated nature of the problem.