Effects of non‐welded interfaces on guided SH‐waves

• Published in: Geophysical research letters Vol. 21; no. 9; pp. 745 - 748
• Main Authors: Nihei, Kurt T., Myer, Larry R., Cook, Neville G. W., Yi, Weidong
• Format: Journal Article
• Language: English
• Published: Washington, DC American Geophysical Union 01.05.1994; Blackwell Publishing Ltd
• Subjects: 01 COAL, LIGNITE, AND PEAT; 02 PETROLEUM; 020200 > Petroleum > Reserves, Geology, & Exploration; 03 NATURAL GAS; 030200 > Natural Gas > Reserves, Geology, & Exploration; Applied geophysics; Boundaries; Contact; Displacement; Downhole methods; Earth sciences; Earth, ocean, space; Exact sciences and technology; Exploration Geophysics; GEOLOGIC STRATA; GEOLOGIC STRUCTURES 011000 > Coal, Lignite, & Peat > Reserves, Geology, & Exploration; Half spaces; INTERFACES; Internal geophysics; Mathematical models; Seismic methods; Seismic surveys; SEISMIC WAVES; Seismology; Shear stiffness; Stiffness; Surface waves and free oscillations; WAVE PROPAGATION; shear strength; interfaces; crosshole methods; Love waves; Mechanical model; SH-waves; elastic waves; phase velocity; seismic methods; propagation; Wave plate; guided waves; discontinuities; half-space
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/94GL00365

The effects of non‐welded interfaces on guided SH‐waves are examined analytically and numerically using the displacement‐discontinuity model to describe the mechanical shear stiffnesses of the interfaces. A modal solution for guided SH‐waves is developed for a layer in non‐welded contact with underlying and overlying half‐spaces. For low interface stiffnesses, the modal solution degenerates to the SH‐plate wave solution and for high interface stiffnesses, to the Love channel wave solution. It is demonstrated that a single non‐welded interface separating two half‐spaces is incapable of supporting an SH‐interface wave. The effects of interface stiffness on the phase velocities and displacement profiles of guided SH‐waves are examined for a low velocity layer in non‐welded contact with bounding half‐spaces using the modal solution and a numerical boundary integral equation code. The results of this analysis demonstrate that the magnitude of the interface stiffness can have a first order effect on the velocities, amplitudes and displacement profiles of guided SH‐waves in a low velocity layer which should make these waves highly detectable in crosshole seismic surveys.