A seismic ray-tracing model performs economic exploration of subsurface structures, which 1) allows amplitude, frequency, mode, and other "synthetic filtering" of the model's calculations and 2) allows model interpolations, approximations, and other "synthetic sensitivity" terminations of ray-tracing...http://www.google.com/patents/US5079749?utm_source=gb-gplus-sharePatent US5079749 - Seismic raytracing method and apparatus
