唐山(1976)和三河——平谷地震(1679)附近的地应力场特征

本文讨论了唐山(1976)和三河-平谷地震(1679)附近的地应力场特征,发现位于震中附近的测点,其应力值比较低,而离开震中以远的测点则应力值比较高.同时还讨论了在唐山市凤凰山和顺义吴雄寺(三河-平谷地震附近)连续几年的测量结果,表明这两个地区震中附近的主应力值随时间变化的幅度不大,而它们的主应力方向随时间则有明显地变化.最后分析了引起震中附近低值应力的原因,并指出研究低值应力异常对地震预报的意义. 

ON STRESS FIELD IN EPICENTRAL AREAS OF 1976 TANGSHAN EARTHQUAKE AND 1679 SANHE-PINGGU EARTHQUAKE

This paper discusses the characteristics of the stress field in the epicentral areasof two large earthquakes -- Tangshan of 1976 and Sanhe-Pinggu of 1679. Stressmeasurements in drill holes give lower values for the points close to the epicentral areas while higher values at points away from them. Meanwhile, a series of stress measurements at two points, Fenghuangshan in Tangshan City and Wuxiongsi of the Shunyi County, nearby the Sanhe-Pinggu epicenter in a period of several years show that the values of principal stress do not vary appreciably with time but their directions are changed obviously. Finally, a preliminary analysis on the cause of low stress values in the epicentral areas has been made and the significance relating to prediction of earthquakes mentioned.