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,△T<150天;对于p>1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。 In this paper, the duration of strong aftershock activity (△ T) and its related problems during the period from 1966 to 1980 in the series of 9th-grade above earthquakes and 12th-order 6-6.9-magnitude earthquakes in the southeastern China and the southwestern Sichuan and Yunnan were analyzed. And gives some empirical results: (1) The difference of △ T length of these sequences is large, and does not seem to be related to the magnitude of the main shock. (2) The length of △ T is related to the magnitude of aftershock frequency attenuation coefficient (p) of the whole sequence. ΔΤ <150 days for sequences with p> 1; ΔΤ> 150 days for sequences with p> 1. And strong aftershock activity terminates near the “inflection point” of the frequency decay curve. The law is extremely complex, inevitably there are exceptions.