FWI model domain angle stacks with amplitude preservation

A non-transitory computer readable storage medium encoded with instructions, which when executed by a computer cause the computer to implement a method comprising:

• obtaining a seismic dataset that is separated into subsets according to predetermined subsurface reflection angle ranges;
• performing, with a computer, an acoustic full wavefield inversion process on each of the subsets, respectively, to invert for density and generate respective density models;
• generating acoustic impedances for each of the subsets, as a function of reflection angle, using the respective density models;
• transforming, using a computer, the acoustic impedances for each of the subsets into reflectivity sections, wherein the transforming includes normalizing the reflectivity sections by their respective bandwidth;
• and
• using, for each of the reflectivity sections, a Fourier transform, discrete Fourier transform, or a fast Fourier transform to calculate an average spectrum within at least one local window that is applied at a same location to all of the reflectivity sections, and determining a bandwidth for each average spectrum.