我国西南及其邻区强震活动与构造应力场的探讨

本文用平面问题的有限元方法,在研究云南地震与应力场关系之后,采用先计算大区域应力场,再计算小区域应力场的分步办法。 首先研究我国西南及其邻区强震活动与构造应力场的关系。计算结果说明:(1)由于印度板块不均匀推挤,在特定的边界条件下,是产生我国西南地区应力场复杂性的主要原因。(2)在印度板块的作用下,断块间运动以及板内大范围内应力场调整是西南地区强震活动的主要因素。(3)通过四个八级以上地震(海源、古浪、察隅:印度、尼泊尔)后应力场调整的研究,未来八级地震的地区有可能在川滇藏或缅甸一带。 

A STUDY OF STRONG EARTHQUAKES AND THE TECTONIC STRESS FIELD OF SOUTHWESTERN CHINA AND ITS ADJACENT AREAS

The present paper has employed the finite-elements method in association with planes to study the relationships between the tectonic stress field and the earthquake occurrences in Yunnan province. Computations are divided into two steps: first for the stress field of a broad region, then for a smaller one. The relationships between the activities of strong earthquakes in Southwest China and its adjacent areas and the tectonic stress field are dealt with in detail.The results of the computation indicate: 1) The uneven pushing from the south due to the Indian Plate is the principal cause of the very eomplicated nature of the tectonic stress field of Southwest China under specific boundary conditions; 2) Under the action of the Indian Plate, relative movements between individual tectonic - blocks and large-scale stress field readjustments within the plate are the principal cause of the activities of strong earthquakes in Southwest China; 3) In the light of the study of the readjustment of the stress field during the 4 earthquakes greater than magnitude 8 (the Haiyuan, Gulang, India-Nepal and Chayu earthquakes), the author has got the impression that future earthquakes greater than magnitude 8 are likely to hit the Shichuan-Yunnan-Tibet or the Burma regions.