Full-waveform inversion (FWI) builds subsurface parameter models by minimizing the residuals between the modeled and observed data. Accounting for the effects of anisotropy is critical for high-resolution imaging of complex structures. We develop an acoustic anisotropic FWI method based on a pure quasi-P-wave (qP-wave) equation. The equation coefficients and their derivatives with respect to Thomsen’s anisotropy parameters (ε and δ) are estimated by least-squares optimization. We derive and analyze the radiation patterns for six parameter classes: the velocity along the symmetry axis v, ε, and δ; the normal moveout velocity vnmo, the anisotropy parameter η, and δ; the horizontal velocity vh, vnmo, and ε; vh, η, and ε; vh, η, and δ; and vh, vnmo, and δ. The parameterization [v,ε,δ] has significant trade-off between ε and δ at the intermediate and wide scattering angles. The anisotropy parameters ε and δ are resolvable at the short scattering angles for the parameterizations [vh,vnmo,ε] and [vnmo,η,δ], respectively. The parameter crosstalk for the parameterizations [vh,η,δ] and [vh,vnmo,δ] is more serious than that for other types of parameterizations. We perform FWI of pure qP-waves in vertical transversely isotropic (VTI) and titled transversely isotropic (TTI) media. Inversion results on the overthrust VTI model and the modified BP TTI model show that the velocity, anisotropy parameters, and tilt angle can be individually reconstructed when other parameters are sufficiently accurate. The multiparameter FWI cannot obtain reliable tilt angles for each type of parameterization. The inversion with the parameterization [vnmo,η,δ] produces v, ε, and δ models with modest accuracy, whereas the parameterization [vh,vnmo,ε] helps to improve the accuracy of v and ε models.

You do not have access to this content, please speak to your institutional administrator if you feel you should have access.