Abstract: The similarity in the seismogenic structure, rupture mode and the focal stress field indicates that the earthquake of magnitude 6.0 occurred in Haicheng on May, 18, 1978 can be regarded as a strong aftershock of the 1975 Haicheng earthquake with magnitude 7.3. After main earthquake there have not been intensive activities of aftershocks. But they toke place much later, it may be explained by the disrupture of the locked section of NNE running active structure.The authors of this paper re,fer the strong shocks taken place within 10 years after the main shock to be the late strong aftershocks. By the synthetic analysis of the geotectonic features and the nature of the whole seismic activity series of the Haicheng earthquake, it is shown that the multi-locking structures must be a necessary background and the locations for generating the late strong aftershocks. Its anomalous precursory, however, was less obvious and appeared only along the direction obliquely aerossing the principal structure in area concerned. Some characteristics of the late strong aftershocks and relevant strike-slip mechanism are slao discussed herein.

摘要： 本文从震源区、发震构造和破裂方式等的相似性,认为1978年5月18日海城6.0级地震是1975年7.3级地震的晚期强余震活动。结合震区地质构造的分析,提出晚期强余震的发生是与残余闭锁区的崩解相联系。因而,主震后,震源区残余的闭锁结构处正是尔后晚期强余震的所在位置。文中还对这种残余闭锁区的形式及其与粘滑机制的关系作了分析。