Abstract: In this paper,the statistic analysis has been made for the distribution of focal depth based on the data of 8935 earthquakes in the Tangshan area,spanninng from 1976 to 1981.The results obtained show that there are not the same in a magnitude and its distribution is closely correlated with the crustal structure.Increasing earthquake depth gradually varies from NE to SW.The earthquake fault belt,which has an.angle of about 8?with the horizontal plain in the lower part and is in accordance with relief boundary in the upper,passes through the crust and down to the Moho.

摘要： 本文根据1976年7月28日到1981年12月唐山地区8935个地震,对其震源深度分布,进行了统计分析。结果表明由东北向西南各区地震震源深度分布都具有优势层,大小地震的优势层也不相同,其分布与地壳结构密切相关,震源深度由东北向西南逐步加深,地震破裂带不但跨越地壳,甚至到莫霍面,在下部构成一个八度多的倾斜底面,上部则随G界面的起伏而变化。