oa Traveltime-based Raytracing for Reflection Waves

A new approach for the raytracing of reflected waves is proposed in this paper. The algorithm is based on the Fermat' s principle and reciprocity and it can be adapted with any type of traveltime calculation technique (Vidale (1988), Saito (1989), Moser (1991), Askawa and Kawanaka (1993)). The method is practical and efficient for complicated subsurface structures. ln accordance with Fermat's principle, raypaths with extremum traveltimes are traced, including the minimum traveltimes (first arrivals); multi-valued traveltimes can be handled with this method. First，using Linear Traveltime lnterpolation (Asakawa and Kawanaka (1993)) for traveltime calculations, the effectiveness of this approach is shown. Then we extend it for the calculations of traveltime/raypaths of normal incident rays. This approach can be also applied to compute traveltime/raypaths of P-S/S-P converted waves or multiple reflections.