Abstract: This paper deals with the stress field in the North China platform and has come to a conclusion that this area shows a difference of the horizontal stress in depth,higher in the eastern part and lower in the western part.Principal horizontal stress from various observation points increases with the depth in this area as well as in the Ordos uplifting region.In addition,the extensional stress appearsat a depth of 500 m.For the Beijing-Tianjing-Tangshan-Bohai area,the maximal principal compressive stress in depth is of ENE or nearly EW direction.At a depth of 30m from the surface the stress orientation relatively scatters and increases with depth below 30m,whereas shows a tendency of rotating.Decreasing of the minimal horizontal principal stress,or more,may he responsible for a trigger of the earthquake associated with a change in stresses.

摘要： 本文分析讨论了华北地区的应力场,认为本区深部水平应力东高西低。平原区各测点的水平主应力值是深度的线性函数,鄂尔多斯隆起区的水平主应力值随深度的增加而增大。平原区500米深度以内至今仍表现为引张性质。 京津唐渤地区,深部最大水平主压应力方向为北东东向或近东西向。30米深度以内,应力方向比较分散,30米以下,随深度增加,主应力方向有旋转趋势。 应力改变触发地震的机制,主要是由于最小水平主应力的减小,或两个水平主应力同时减小。