Abstract: The urban area in the eastern China region is mostly covered by the relatively thick loose Quaternary deposits,below which,in many cities,there exist many considerably large buried faults.In these thick-Quaternary-covering areas,does the date of the upper layers dislocated by the buried faults represent the latest faulting? In this paper,based on the integrated analysis on the data of geology,geophysics and earthquakes of cities in the east of China,including Xingtai and Tangshan,we discussed the relation between the upper offset point and the latest activity times of the buried faults in these areas covered by thick Quaternary.Our study shows,in the area with very thick recent deposits in East China,one should not determine the latest faulting of one fault fully according to the younger layers displaced by the fault.To a fault running through the area covered with thick young deposits,its latest active period should be determined comprehensively by the tectonic settings,the controlling of the fault to the young strata,the youngest layer displaced by the fault,the thickness of the young deposits,seismicity and modern tectonic stress field,etc.

Key words: buried fault, the upper offset point, the activity times

摘要： 中国东部城市地区大多为较厚第四系松散物覆盖区,许多城市附近发育了具有相当规模的隐伏断裂。在这些第四系较厚覆盖区发育的隐伏断裂的上断点是否代表了断裂的最新活动时代?文中通过对邢台、唐山等发生过强震的中国东部城市附近地区地质、地球物理、地震活动、地形变等资料的综合分析,来讨论这些较厚第四系覆盖区隐伏断裂的上断点与断裂的最新活动年代的关系问题。初步分析表明,作为邢台地震和唐山地震发震断裂的新河断裂和唐山断裂带,并不象其上断点显示的为晚更新世不活动断裂或者为局部活动段,而均为大型活动断裂。由此认为,在中国东部沉积层较厚地区,不能完全根据断裂断错的最新地层确定断裂的最新活动时代。对于一条穿过新沉积较厚地区的断裂,其最新活动时代应根据构造背景、断裂对新地层的控制作用、断错最新地层、新地层沉积厚度、构造地貌、地震活动、地形变、现今构造应力场等综合判定。

关键词: 隐伏断裂, 上断点, 活动时代