Common reflection azimuth migration

Method for migration of seismic data into datasets having common azimuth angle at the reflection point. A velocity model is selected that prescribes subsurface P and/or S wave velocities including any required anisotropy parameters. For shot locations on a surface grid, rays are traced on to a 3D grid of points in a target region of the subsurface. At least the travel times of the rays and their dip angles at each subsurface point are stored in computer memory as they are computed. Using the stored ray maps, the seismic data are migrated into seismic image volumes, each volume being characterized by at least an azimuthal angle bin, the azimuthal angles being computed from said ray dip angle information.