Time-migration velocity analysis by velocity continuation

Time-migration velocity analysis can be performed by velocity continuation, an incremental process that transforms migrated seismic sections according to changes in the migration velocity. Velocity continuation enhances residual normal moveout correction by properly taking into account both vertical and lateral movements of events on seismic images. Finite-difference and spectral algorithms provide efficient practical implementations for velocity continuation. Synthetic and field data examples demonstrate the performance of the method and confirm theoretical expectations.