慢度平方三角网格模型VTI介质二维QP波各向异性立体层析反演

2D QP anisotropic stereo-tomography for VTI media in triangulated model

基于慢度平方三角网格剖分模型下的各向异性射线扰动理论,建立了具有垂直对称轴的横向各向同性(VTI)介质中二维QP波立体层析所需的FRECHET导数矩阵,实现了慢度平方三角网格模型的VTI介质二维QP波各向异性立体层析.考虑到各向异性参数是影响地震波运动学特征的次一级因素,制定了先反演慢度再反演各向异性参数的反演策略.由于慢度平方三角网格模型的稀疏性,使得数据空间对模型空间的FRECHET导数矩阵规模被大幅压缩,在降低了计算成本的同时也很好的保证了界面位置、背景慢度、各向异性等各个参数的反演精度.理论数据算例证实了FRECHET导数的正确性和反演策略的合理性.

Based on the anisotropic ray perturbation theory in slowness squared triangulated model,a 2D QP wave anisotropic stereo-tomography for VTI media is presented.Due to the sparsity of slowness-squared triangulated model,the scale of FRECHET derivative matrix of stereo-tomography is greatly reduced thus the computational cost is significantly cut down.Meanwhile,the accuracy of a joint inversion of the interface position,background velocity and anisotropic parameters is pretty good.The numerical examples demonstrated the correctness of the presented Frechet derivatives and the feasibility of the inversion strategy.