Abstract: In this paper the geopotential harmonic coeffients derived from satellite tracking by Wagner are studied and divided into two parts: one with n≤11,correlated with largescale mantle convection; the other with 12≤n≤25,correlated with small-scale convection.The subcrustal stress field caused by mantle convection under the study region has been obtained,which is a regular symmetrical compressional stress field,with a compressive field central at.the Linfen-Hondon area (111.5°E; 36°N).The magnitude of stress for this region is about 0.2—0.75×10⁸dyn·cm^-2.The pattern of the epicentral distribution for major shocks and the focal mechanism solutions are almost similar to those of the subcrustal stress field,especially for Tangshan and Haicheng earthquakes.It is concluded that the subcrustal stress field caused by small-scale mantle convection controls seismic activities,even those strong quakes that occurred in the study region at high tide,recently.

摘要： 本文分析了魏格纳等求得的重力位球谐系数,得出n≤11阶系数与大尺度地幔对流相关,而12≤n≤25阶系数反映小尺度地幔对流;计算了小尺度地幔对流引起的华北地区壳下应力场,该应力场具有挤压性质,挤压中心在山西临汾—洪洞一带(111.5°E;36°N),应力大小为0.2—0.75×10⁸达因·厘米^-2,整个应力场具有规则的中心对称特征;壳下应力场的几何特征与震源机制解的结果、大震裂缝走向与错动方式、地震的空间分布等均彼此具有良好的一致性,对唐山与海城地震,这种一致性尤为明显。看来,似乎小尺度地幔对流及其造成的壳下应力场对包括目前这次强震高潮在内的华北地区地震的孕震过程起着控制作用。