Abstract: Two destructive earthquakes occurred in the southern Liyang region,Jiangsu Province in 1974 and 1979,with magnitude 5.5 and 6,respectively. The 1979 Liyang earthquake with magnitude 6 is the largest earthquake in the land area in the province in modern times. The interval between the two earthquakes is 5 years,and their meizoseismal areas overlap basically,indicating that the seismogenic structures of the two earthquakes belong to a same active fault. Based on field investigations,many scholars believed that the seismogenic structures of these two earthquakes were related to the NNE-trending Maodong Fault. In recent years,more in-depth studies were conducted in this region,e.g.shallow seismic prospecting,high density electric prospecting,drilling exploration and seismic geological investigation. And with the accumulation of data and the precise location of aftershocks in the earthquake region,a clearer understanding has been gained of the seismogenic fault of the Liyang earthquakes. The main shocks and the aftershocks of the two earthquakes are all distributed along the Jintan-Nandu Fault located 2km east of the Maodong Fault. Both main shocks are located at the intersection of the southern segment of Jintan-Nandu Fault and the near-EW-trending Liyang-Nandu Fault. Thus,the authors conclude that the Jintan-Nandu Fault is the major seismogenic fault for both Liyang earthquakes.

Key words: Liyang earthquake, Jintan-Nandu Fault, seismogenic fault, aftershock activity image

摘要： 1974年、1979年在江苏省南部溧阳地区相继发生了震级分别为5.5级和6级的2次破坏性地震,其中1979年的6级地震是现代发生在江苏省陆域内震级最高的地震。2次地震相隔5年,极震区基本重合,说明2次地震的发震构造属同一活动断裂。不少学者经过考察认为这2次地震的发震构造与NNE走向的茅东断裂有关。近年来,许多研究者在溧阳震区开展了大量浅层人工地震探测、高密度电法、钻探及地震地质考察,随着资料的积累以及对震区余震的精确定位,人们对溧阳地震的发震断裂有了更清晰的认识。这2次地震的主震及其余震均沿茅东断裂以东2km的金坛-南渡断裂分布,2次主震震中均位于金坛-南渡断裂南段与近EW向的溧阳-南渡断裂相交会的区域内。因此,笔者认为这2次溧阳地震的发震主断裂应为金坛-南渡断裂。

关键词: 溧阳地震, 金坛-南渡断裂, 地震断层, 余震活动图像