Full-waveform inversion results when using acoustic approximation instead of elastic medium

Seismic marine data inversion is a very heavy process, especially for the 3D seismic case. Often approximations are made to limit the number of physical parameters or to speed up the forward modeling. Because the data are often dominated by uncoverted P waves, one popular approximation is to consider the earth as purely acoustic: no shear modulus; even sometimes with constant density. Nonlinear waveform seismic inversion consists in iteratively minimizing the misfit between the amplitudes of the measured and the modeled data.