RDOASP is the range-dependent version of OASP. RDOASP uses a Virtual Source Approach for coupling the field between range-independent sectors, basically using a vertical source/receiver array, and a single-scatter, local plane wave handling of vertical discontinuities [21]. In contrast to the similar approach of the elastic PE, VISA properly handles seismic conversion at the vertical boundaries. The solutions compare extremely well with PE solutions for week contrast problems, and with full boundary integral approaches for several canonical elastic benchmark problems [20,21].
The frequency integral is evaluated in the Post-processor PP.