Abstract: The mechanical nature of 121 earthquake faults, the strikes of 40 events and the directions of fracture propagation of 15 events are discussed in this paper.On this background,some relationships between the strikes of intraplate earthquake faults in North China and the distributions of uplifted zones of uppermost mantle have been found, e. g. within these zones the earthquake faults run nearly parallel tp their elongation, while on their opposing sides the earthquake faults are mainly perpendicular to them. However, it seems to be that the mechanical nature and the direction of fracture propagation are not controlled by the pattern of rising of uppermost mantle, but coincide with the general characteristic feature in the eastern part of China continent.The authors hold that there exist two types of geodynamical processes in North China, the one is, the North China fault blocks are subjected to a compression trending NEE-SWW due to the eastward movement of the Xizang (Tibet) block, the other is, the diapirism of the upper most mantle and the gravity isostasy make the continental crust of North China thinning and its certain parts having lense-shape. The characteristics mentioned above and the cause of the high seismicity in North China could be explained by the superimposition of these two dynamical processes.

摘要： 本文研究了华北121个地震断层的错动方式,40个地震断层的走向,15个地震断层的破裂方式与扩展方向。在此基础上发现了华北板内地震断层特征与上地幔隆起带之间的某些规律性联系。作者认为:由于上地幔软流圈的异常活动,上地幔顶部隆起的底辟作用以及重力均衡作用,华北大陆地壳正在经历着一种透镜化的拉薄改造过程,据此可以解释华北板内地震断层的特征,并进而探讨华北板内地震高强度性的原因。