The Challenge of Short-wavelength, High-contrast Velocity Anomalies

Conventional velocity estimation, based on post migration residual moveout, works very well when the velocity structure of the Earth is smooth enough in the lateral directions. This is true even when the initial velocity model is far from correct. Stated another way, long wavelength lateral velocity errors are not a significant challenge anymore. However, once the velocity varies significantly in the lateral directions at scales approaching or less than a few wavelengths, residual moveout estimation plus reflection tomography will often fail to improve velocity models.