南海及邻域现代构造应力场的数值模拟

A NUMERICAL SIMULATION OF THE RECENTTECTONIC STRESS FIELD IN SOUTH CHINA SEA AND ITS ADJACENT AREAS

将南海及邻域的现代构造应力问题视为弹性板的平面应力问题,用有限元法对现代构造应力场进行计算。以海沟俯冲带为主要边界,全区离散成1130个单元和612个节点。根据各单元的地壳厚度、P波速度、密度以及泊松比将区内地壳分成5种类型。考虑了4种外力作用方式,这些外力分别反映了印澳板块和菲律宾海板块对研究区的作用力大小和方向。将计算得出的最大主压应力方向与震源机制解的P轴方向进行比较,选择一种和后者符合最好的边界条件和计算结果作为可取模式,并分析了南海及邻域现代构造应力场的分布格局。

The Recent tectonic stress field in South China Sea and its adjacent areas is considered as a problem of plane stress on elastic plate, which is calculated by finite element method. Taking the trench - subduction zone as a main boundary, the studied region is composed of 5 parts. According to the different crustal thickness, P - wave velocity, density and Poisson' s ratio.it is divided into 1130 trigonal elements with 612 points. Four modes of boundary forces, which represent the forces exerted on the studied region by Indian-Australian Plate and Philippine Sea Plate respectively , are tested. The direction of maximum principal compressive stress obtained from the calculation is compared with that of P-axis from focal mechanism solutions. The model which fits most satisfactorily with focal mechanism is selected as an available model. At last, the distribution framework of the recent tectonic stress field in South China Sea and its adjacent areas is analysed in this paper.