An exact anelastic model for the free-surface reflection of P and S-I waves

Bulletin of the Seismological Society of America
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Abstract

Exact anelastic solutions incorporating inhomogeneous waves are used to model numerically S-I and P waves incident on the free surface of a low-loss anelastic half-space. Anelastic free-surface reflection coefficients are computed for the volumetric strain and displacement components of inhomogeneous wave fields. For the problem of an incident homogeneous S-I wave in Pierre shale, the largest strain and displacement amplitudes for the reflected P wave occur at angles of incidence for which the particle motion for the reflected inhomogeneous P wave is elliptical (minor/major axis = 0.6), the specific absorption (QP−1) is greater (300 per cent) and the velocity is less (25 per cent) than those for a corresponding homogeneous P wave, the direction of phase propagation is not parallel to the free surface, and the amplitude of the wave shows a significant increase with depth (6 per cent in one wavelength). Energy reflection coefficients computed for this low-loss anelastic model show that energy flow due to interaction of the incident and reflected waves reach maxima (30 per cent of the incident energy) near large but nongrazing angles of incidence. For the problem of an incident homogeneous P wave in Pierre shale, the inhomogeneity of the reflected S wave is shown not to contribute to significant variations in wave field characteristics over those that would be expected for a homogeneous wave.

Publication type Article
Publication Subtype Journal Article
Title An exact anelastic model for the free-surface reflection of P and S-I waves
Series title Bulletin of the Seismological Society of America
DOI 10.1785/BSSA0790030842
Volume 79
Issue 3
Year Published 1989
Language English
Publisher Seismological Society of America
Contributing office(s) Earthquake Hazards Program
Description 18 p.
First page 842
Last page 859
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