Abstract: Some dynamic problems of recent tectonic fracture were studied by analysing seismi-city and seismic mechanism parameters and the rate of slip and apparent stresses for majcr shear fracture belts in the North China fault block region.Several points can be covered as:1. The recent crust fracture system formed by seismic activity and its distribution look like stable shear fracture network and the direction of the line dividing equally an acute angle of the network points to nearly east-west,which shows that principal stress field would be from nearly east-west horizontal compressive stress field in whole region.2. The strike slip and near strik slip faulting among seismic faults and horizontal and nearly horizontal maximum and minimum stress in soucrce region are dominant,but some oblique and dip slip faulting,and oblique and vertical stress exist and can not be neglected,according to the results of the mechanism solution for 92 events in this region,which shows the characteristics of combinatory action of horizontal or nearly horizontal force with local oblique or vertical force applied on the North China fault block region.3. The rate and grade of seismic slip along major shear fracture belts computed from seismic moment are smaller than 0.1 cm/yr. which implys that the regional crust faulting may be formed and local shear faulting may be a main way of releasing stress from earth's crust.4. The average seismic tectonic stress of medium-sized events and the shear stress around small circular crack seem to be up to from several tens of to several hundreds of bars in magnitade.

摘要： 通过华北断块区的地震活动、空间分布、地震断裂力学参数分析和剪切破裂带地震滑动速率及应力计算等研究了该地区现代构造断裂的动力学问题。基本结果如下:(1)由地震活动及其分布所构成的深部地壳的现代断裂为一稳定的剪切破裂网络体系。(2)由震源机制资料得到本区地震断层多属走滑型和近走滑型,震源区主应力为水平力和近水平力。但斜滑型断层和倾滑型断层以及斜力和近垂直力也占有不可忽视的比例。(3)由地震矩估算出剪切破裂带的平均滑动速率均小于0.1厘米/年。(4)用中小地震估算本区地震构造力约为几十——几百巴量级。