An efficient wavefield inversion for transversely isotropic media with a vertical symmetry axis

Conventional FWI aims at retrieving a high-resolution velocity model directly from the wavefields measured at the sensor locations forming a highly nonlinear optimization problem. Considering the Earth is truly anisotropic, a multi parameter inversion imposes additional challenges in exacerbating the Null space problem and the parameter tradeoff issue. Alternatively, we formulate an optimization problem to reconstruct the wavefield in an efficient matter in the background model by using an enhanced source function (which includes secondary sources), and thus, reducing updates to the model. In this setup, the inversion for the wavefield is linear. The inversion for the anisotropic parameters are handled in a separate optimization using the wavefield and the enhanced source function. We show the effectiveness of this approach in reducing parameter tradeoff and in inverting for an anisotropic Marmousi model.