Refraction Seismics - Diving Waves Instead of Headwaves

The high-velocity branch in refraction seismic observations is generally considered as a head wave traveling along the plane interface between a homogeneous overborden and a homogeneous half space (the substratum). Head waves satisfy Snell's law, and the entire ray path consists of straight segments. Travel times of refracted arrivals can thus be dealt with in the ray-geometric approximation. This is the basis of all (structural) interpretation rnethods.