1966年3月河北省南部发生的邢台大地震是一个前震多、主震强、余震频繁、衰减有起伏、延续时间长的地震序列。在它的活动过程中曾经发生过多次强余震活动的反复。直到将近十六年之久的1981年11月9日又发生了这次5.8级强余震。仅到11月30日的22天内就发生了700多次小地震,其中M_1≥4级地震2次,又形成了邢台大震群中的一个子序列。从测定的基本参数看来(图1),它们都分 The March 1966 Xingtai earthquake in southern Hebei Province was a series of earthquakes with a large number of foreshocks, frequent main aftershocks, frequent aftershocks, and decay and undulation. There have been many repetitions of strong aftershocks during its activities. The 5.8-magnitude aftershock took place on November 9, 1981, nearly sixteen years ago. More than 700 small earthquakes occurred within 22 days of Nov. 30, of which M_1 ≥ 4 earthquakes twice and a sub-sequence of Xingtai large-scale earthquake swarm formed. From the measurement of the basic parameters (Figure 1), they are divided