I use the acoustic wave equation for transversely isotropic media with vertical symmetry axis (VTI media), to generate synthetic VTI data for an anisotropic version of the Marmousi model. This acoustic equation, though it represents a physically impossible medium, provides an extremely accurate approximation of the widely used elastic wavefield. The anisotropic Marmousi model has the same NMO velocity as the original Marmousi model and an anisotropy distribution that possesses the same layering characteristics as the velocity model. Interval spans the range of 0 to 0.27, which are values that are commonly observed in practice. The traveltime and amplitude differences between the synthetic seismograms of this new anisotropic model and those produced by the original isotropic Marmousi data set are quite apparent. As a result, a prestack isotropic migration failed to properly image the anisotropic data when using the exact original velocity model.