A refraction survey over a two-layer crust gives an upper-layer speed

PHYSICS · Multi-part · Fermi University Physics · Earth, Climate & Energy Physics · Seismology, tectonics and geodynamics · Seismology, tectonics and geodynamics

The Solid Earth, Ch Rays and travel times: from arrivals to a layered planet

Problem

A refraction survey over a two-layer crust gives an upper-layer speed v1=6.0 km s−1v_1 = 6.0\,\mathrm{km\,s^{-1}}, a lower-layer speed v2=8.0 km s−1v_2 = 8.0\,\mathrm{km\,s^{-1}}, and a head-wave intercept time τ=4.0 s\tau = 4.0\,\mathrm{s} read from the extrapolated first-arrival line. ((a)) Find the critical angle ici_c. ((b)) Find the thickness hh of the upper layer. ((c)) Find the crossover distance xcx_c beyond which the head wave is the first arrival.

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