Abstract: This paper deals with the geological factors affecting the distribution of seismic intensity in the Beijing region during the Tangshan earthquake. It is suggested that the geological factors leading to the intensity anomalies in the Beijing region include mainly liquefaction of sandy soil, faults and buried hills. As the liquefaction of saturated sandy soil caused by the earthquake is related with the permeability of groundwater, earthquakes tend to build up easily the pressure in the region with less permeability due to the showness of dissipation. In general, the buried hills would play a role in the amplification of ground shock owing to its various relief.The data of historical earthquakes in Beijing and its adjacent regions indicate that the effect of several earthquakes on a given region appeared to have some kind of synchronous intensity anomalies. Therefore, this repetition anomalies may be regarded as a reflection of the geological factors having a long-term effect on the region under investigation. Hence, we are led to the conclusion that the geological conditions of the areas of intensity anomalies, especially the areas of frequent historical earthquakes, should be studied in detail so that they could offer an important approach to estimate seismic intensities and to prevent and resist future earthquake hazards.

摘要： 唐山地震导致北京地区出现烈度异常区的主要地质因素是砂土液化、断层和潜山。砂土液化分布于地势低洼、新近沉积的饱和砂层地区,并位于地下水埋藏浅和迳流滞缓地区。断层控制异常区呈带状分布。潜山的影响主要在于其形态引起的地震动“放大”作用。几次地震对某些地区的影响,常重复出现烈度异常,反映在该地区具有长期起作用的地质因素。