f 3D depth migration via under-relaxation

The future of seismic processing in 3-D will require algorithm design for supercomputers. The general principles of such methods will be suitable for most types of parallel computers that can meet the challenge of dealing with the large 3-D data volume. In recent years we have seen an increase in the use of 3-D migration methods by means of two-pass and one-pass or splitting methods. Two pass migration, a method that replaces the true 3-D case with an approximation that solves a series of 2-D migrations in orthogonal directions (Brown, 1983 ; Dickinson, 1988, Yilmaz, 1987), has been used almost exclusively and in some operational environments where the complete 3-D volume can be accommodated the so called a one pass or an alternating direction implicit (ADI) 3-D approach to migration can be used .