A SEISMIC SCALE-MODEL STUDY OF REFRACTION ARRIVALS IN A THREE-LAYER STUCTURE.
Special technical rept.,
PENNSYLVANIA STATE UNIV UNIVERSITY PARK DEPT OF GEOLOGY AND GEOPHYSICS
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One of the uses of seismic waves is in the study of crust-mantle relationships. A crustal model having a narrow intermediate-velocity layer was postulated for comparison with another model, previously studied, having a narrow region of constant velocity gradient. Both models have their narrow regions bounded above by a low-velocity region and below by a region of higher velocity. It was shown experimentally that the same relationship between the velocity gradient and cutoff frequency was found for both studies, with the cutoff frequency being 1.7 times the velocity gradient. The cutoff frequency is defined as the frequency at which the spectrum of the refracted arrival begins to fall off rapidly from the spectrum of the direct wave. A part of the effect is accounted for by noting the theoretically expected fall off of the refracted from the direct spectra of 6 dboctave. Author
- Geology, Geochemistry and Mineralogy