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Seismic waves on a boundary: refraction method. Earth Physics EPSC 320 Autumn 2010. Seismic refraction method. Snell's law sin(i p )/ 1 = sin(i s )/ 1 = sin(r p )/ 2 = sin(r s )/ 2 = p, the ray parameter. Ray paths in 1 layer.
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Seismic waves on a boundary: refraction method Earth Physics EPSC 320 Autumn 2010
Seismic refraction method Snell's law sin(ip)/1 = sin(is)/1 = sin(rp)/2 = sin(rs)/2 = p, the ray parameter
Ray paths in 1 layer Note V1 > V0 required for head wave
Waves in a 1 layer* model: V1 < V0 * one layer above a halfspace V1 < V0
... at 140 ms Direct, reflected, refracted and 'head' waves
Refractions and reflections ...a ray model Snell's law in a 1-layer structure
The interpretation http://www.epa.gov/oust/pubs/esa-ch3.pdf
Global scaling As seismic velocities generally increase with depth, the P-waves and S-waves are refracted back to the surface. We can interpret the travel-time curves as an infinite number of infinitesmally thin layers in spherical shells..
Reference Most of the nice graphical images used in this presentation are taken from the seismic noteset: http://galitzin.mines.edu/INTROGP/MISC/seisnotes.pdf
