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Title: Elastic interface waves along a fracture

Abstract

Non-welded interfaces can be treated as a displacement discontinuity characterized by elastic stiffnesses. Applying this boundary condition to a generalized Rayleigh wave, it is shown that a fast and a slow dispersive wave can propagate along the fracture, even when the seismic properties of the rock on each side are identical.

Authors:
;
Publication Date:
Research Org.:
Department of Material Science and Mineral Engineering, University of California, Berkeley and Earth Sciences Division, Lawrence Berkeley Laboratory, Berkeley, California
OSTI Identifier:
5717613
Resource Type:
Journal Article
Resource Relation:
Journal Name: Geophys. Res. Lett.; (United States); Journal Volume: 14:11
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; ROCKS; FRACTURES; WAVE PROPAGATION; ELASTICITY; INTERFACES; RAYLEIGH WAVES; SEISMIC WAVES; FAILURES; MECHANICAL PROPERTIES; SEISMIC SURFACE WAVES; TENSILE PROPERTIES; 580300* - Mineralogy, Petrology, & Rock Mechanics- (-1989)

Citation Formats

Pyrak-Nolte, L.J., and Cook, N.G.W. Elastic interface waves along a fracture. United States: N. p., 1987. Web. doi:10.1029/GL014i011p01107.
Pyrak-Nolte, L.J., & Cook, N.G.W. Elastic interface waves along a fracture. United States. doi:10.1029/GL014i011p01107.
Pyrak-Nolte, L.J., and Cook, N.G.W. 1987. "Elastic interface waves along a fracture". United States. doi:10.1029/GL014i011p01107.
@article{osti_5717613,
title = {Elastic interface waves along a fracture},
author = {Pyrak-Nolte, L.J. and Cook, N.G.W.},
abstractNote = {Non-welded interfaces can be treated as a displacement discontinuity characterized by elastic stiffnesses. Applying this boundary condition to a generalized Rayleigh wave, it is shown that a fast and a slow dispersive wave can propagate along the fracture, even when the seismic properties of the rock on each side are identical.},
doi = {10.1029/GL014i011p01107},
journal = {Geophys. Res. Lett.; (United States)},
number = ,
volume = 14:11,
place = {United States},
year = 1987,
month =
}
  • A wavelet analysis is performed on seismic waveforms of elastic interface waves that propagate along a fracture. The wavelet analysis provides a direct quantitative measure of spectral content as a function of arrival time. The authors find that the spectral content of the interface wave signals is not stationary, but exhibits increasing frequency content for later arrival times, representing negative velocity dispersion. The dispersion increase from {minus}11 m/sec/MHz to {minus}116 m/sec/MHz as the stress on the fracture is increased from 3.5 kPa to 33 MPa. The negative velocity dispersion agrees with predictions from the displacement-discontinuity theory of the seismic responsemore » of fractures, and can be used to fit fracture stiffness. 16 refs., 3 figs., 1 tab.« less
  • Experimental and theoretical investigations of the longitudinal propagation of magnetoplasma surface waves along a semiconductor-metal interface across a magnetic field B are reported. (AIP)
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  • The theory of resonance reflection is formulated for elastic waves at the interface between two anisotropic media under conditions of sliding contact. The phenomenon under study arises in the close vicinity of a certain incidence angle for which the tangential wave vector component of the bulk wave is equal to the real part of the wave vector for the leaky mode. The relations presenting the behavior of wave-response parameters near the leaky mode resonance are derived for arbitrary crystal anisotropy. In particular, the behavior of reflection, transmission, and transformation of the bulk mode to the nonuniform one is discussed. 18more » refs.« less
  • The specific features of acoustic wave reflection are analyzed at the interface between two hexagonal crystals with a sliding contact between them. Attention is focused on the angles of incidence corresponding to excitation of the leaky wave. The conditions supporting the existence of leaky waves are found. The expressions illustrating the behavior of plane wave transformation coefficients for reflection, refraction, and excitation of interfacial oscillations are found in analytic form. In addition, the features of nonmirror reflection are studied for a slightly diverging acoustic beam having initially a rectangular profile. The study deals with the case when the tangential projectionmore » of the {open_quotes}mean{close_quotes} wavevector for the beam is close to or coincides with the real part of the wavevector of the leaky wave. 9 refs., 10 figs.« less