Which wave path is fastest?
Snells's Law describes the relationship between the angle of incidence of a seismic wave passing through a boundary between two different media. In this model of increasing velocity with depth, the critically refracted seismic rays speed up with depth. Velocity boundaries redirect the seismic waves until they reach a critical angle and return to the surface.
- When waves pass through a boundary of two different media they are refracted
- When the wave passes through a less-dense to more-dense media it bends toward horizontal
- Deeper waves move faster along the deeper interfaces and can arrive at distant stations sooner than shallower waves