Paper Summary

Three expanding domain methods are studied which include: (1) constant velocity layer, (2) eikonal equation solver and (3) amplitude comparison. The layer method requires the least traveltime computing overhead but has a loose domain size. The eikonal equation solver method gives a relatively compact domain size but requires relatively expensive traveltime computation. The amplitude comparison method is accurate and less expensive. The expanding domain method is used for efficient finitedifference Reverse Time Migration (RTM).