L18_SeismicRefractionI-page6

L18_SeismicRefractionI-page6 - Mapping vertical contacts...

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6 Applied Geophysics – Refraction I Horizontal vs. vertical velocity contrasts Use a long-offset shot • Leave the geophones fixed and move shot to greater offset In horizontal layers case the shape of the traveltime curve is unchanged, just shifted in space. In vertical velocity contrast case the crossover distance remains fixed but is time shifted. Applied Geophysics – Refraction I
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Unformatted text preview: Mapping vertical contacts Small offsets A vertical step causes an offset on the traveltime curve 1 2 1 2 2 1 2 V V V TV z t − ∆ = • Diffractions link the two head wave curves • Depth, z1, is calculated from the intercept in the usual way • The relation of velocity to the slope remains unchanged • The offset can be calculated from the time offset, ∆ T...
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This note was uploaded on 01/07/2012 for the course PHYSICS 384 taught by Professor Wei during the Spring '09 term at SUNY Stony Brook.

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