1. A method comprising: using an approximation in a computer implemented iterative geophysical data inversion, wherein the approximation is other than source encoding, and the approximation is made in at least one of (i) processing or selecting measured data to invert, or (ii) parameterization of a subsurface model, or (iii) simulation of synthetic data to compare to measured data; and varying, with the computer, the approximation in iterative cycles of the iterative geophysical data inversion, wherein the varying causes an artifact in updated subsurface models to not coherently add in leading to a final subsurface model as the iterative geophysical data inversion progresses.