三分量地震波场的近似解析离散模拟技术

A NEARLY-ANALYTICAL DISCRETIZATION MODELLING TECHNIQUE OF 3-COMPONENT SEISMIC WAVE-FIELDS

首先将二维各向异性介质中地震波动二阶偏微分方程组降为关于时间ｔ的一组一阶偏微分波动方程组，然后利用Ｔａｙｌｏｒ展式和插值逼近的方法构制了一种与有限元法、反射率法、射线追踪法、有限差分法等传统方法不同的近似解析离散方法（ＮＡＤＭ）．对双层各向同性介质以及横向各向同性介质中的三分量地震波场进行了模拟，并与传统的有限差分法作了比较，结果表明ＮＡＤＭ算法可行．

The second-order elastic wave equations In 2-D inhomogeneously anisotropic media are changed into a system of first-order partial differential equations for time t. A new nearlyanalytic discretization method(NADM),which is different from these conventional methods──finite element method, reflectivity method, ray tracing method, and finite difference method(FDM), etc., is developed via using the Taylor expansion and interpolating approximation method. The 3-component seismic wave-fields in two layered isotropic and transversely isotropic media(TIM) are simulated by the algorithm designed in this psper.The numerical results, computed by the NADM method and the coventional finite-difference method, are compared. It shows that the new method is feasible and satisfactory.