f Migration to zero-offset in variable velocity media

Migration to Zero-Offset (MZO) or Prestack Partial Migration (PSPM) transforms prestack data into zero-offset data and is equivalent in a constant velocity medium to the normal moveout correction (NMO) followed by the dip moveout correction (DMO) applied as a single step process. For media with lateral velocity variation or with sharp increase of velocity in depth the migration to zero-offset process cannot be split in NMO followed by DMO, but must be applied as a single process.