A NUMERICAL SIMULATION OF THE PRESENT TECTONIC STRESS FIELD OF CHINA AND ITS VICINITY
Wang Su-yun Chen Pei-shan(Institute of Geophysics, State Seismological Bureau)
A calculation of present .tectonic stress field of China and its vicinity as a plane stress problem has been made by means of the finite element method. The crust of this region is taken as an elastic plate which composed of 12 parts with different Young's modulus E, Poisson's ratio v and thickness T. The whole region is divided into 288 trianglar elements. Five models of boundary conditions of stress and displace-ment have been considered, which represent relative values of the stress applied to the region inside China and its vicinity by the Indian ocean plate, the Pacific plate and the Philippine sea plate respectively. The values of maximum shear stress obtained from calculation have been compared with the distribution of the strong earthquakes, and the directions of the maximum compressive principal stress with that obtained from focal mechanism solutions. The boundary condition which agrees most satisfac-torily with the actual has been selected as an available model. The result shows that the driving force seems to be mainly due to the Indian ocean plate. It is about two times larger than that of the Pacific plate and the Philippine sea plate respectively.