Abstract: Observations suggest that at the beginning of May, 1976, the crustal media in the Tangshan M=7.8 earthquake epicentral area has undergone some important event which caused abrupt changes in anomalies such as ground deformation, water level, gravity, electrical restivity, etc. From the viewpoint of tectonic collapse, all these anomalies can be related to the occurrence of tensile fractures close to the surface.Since this type of tensile fractures was caused by local uplift on the main fault, they extended parallel to it. Continuous observation data of stress field strongly support this inference.

Key words: Tectonic collapse, Tangshan earthquake, Precursory anomalies

摘要： 唐山7.8级地震震中区的观测资料表明,1976年5月初,地壳岩层中发生了重要的事件,它使地形变、地下水位,重力、地电阻率等方面的异常突然地加速。从构造塌陷的角度看,这些异常加速都可以用唐山7.8级地震主断裂上出现了大量张裂隙来解释,这种张裂隙发生在地表附近,其延伸方向与断裂平行,是岩层局部向上凸起造成的。地应力方面的资料与此相符。

关键词: 构造塌陷, 唐山地震, 震前异常