In this study, a frequency-domain elastic full waveform inversion algorithm for 2-D VTI media has been developed. The forward problem used in this inversion algorithm is simulated by applying frequency domain finite difference method, which is a fast approach for multi-source and multi-receiver acquisition. For the anisotropic inversion of VTI media, five elastic constants (c11, c13, c33, c44 and density) have to be dealt with. In this paper, the gradients of four elastic constants are calculated in matrix forms. To accelerate the convergence rate of inversion, the pusdo-Hessian is also implemented in the objective function. The inversion results in the paper show that parameters c11, c13 and c33 can be inverted properly, yet the inversion result of c44 is not satisfying.
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