Abstract: On the basis of comparision of the distribution of intensity for two earthquakes occur ring in the Liyang area with a magnitude of 5.5 (Feb.22,1974) and of 6.0 (Sept.9,1979),it has been found that the principal axis of their magistoseismic area is in a WNW-ESE direction and the shapes they take are not in agreement with the isoseismal lines.In this paper,the writer has suggested that the disagreement of this sort may be explained by the widespread distribution of the basement soil characteristic of muddy quality mild clay in the eastern part of the epicentral area.Four categories of the basement soil have been presented according to characterized soil.Quaternary sediments and underground water table and the like.The writer has attempted to investigate the distribution of intensity and to reconstruct the map for intensity distribution for the purpose of elimination of site-related effect on intensity distribution and of emphasis on underlying role of structures when putting various intensities that are situated in four categories of basement soil under the same classification (Ⅲ).It has been concluded that the distribution in point is strictly dependent on those faults where earthquakes may attend and that there is a tendency to the same direction shown by intensity isolines for highly harzard area and magistoseismic one.

摘要： 本文比较了溧阳原地重复的两次中强地震烈度分布和衰减特征,并将震区划分为四种不同类型的地基土。对两次地震极震区与整个破坏区烈度线在轴向上不协调原因加以讨论,认为以淤泥质亚粘土为主的Ⅳ类地基土在震中区东部大面积分布是其主要原因。重新勾绘了极震区的烈度线,以排除场地条件对烈度分布的不均匀影响。经“归一法”处理,显示出烈度分布较严格地受发震断层控制,极震区的烈度形态与整个等烈度线形态趋于一致。