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Okaya & Christensen 2002
Okaya, D.A. and Christensen, N.I. (2002). Anisotropic effects of non-axial seismic wave propagation in foliated crustal rocks. Geophysical Research Letters 29: doi: 10.1029/2001GL014285. issn: 0094-8276.

Seismic wave propagation within the crust is usually in directions not parallel to inherent rock symmetry axes due to geologic dips of structures and/or oblique-to-arcuate raypaths. We use Christoffel equations and petrophysically measured velocities of crustal metamorphic rocks to examine anisotropic velocities and traveltime effects as functions of non-axial propagation. P- and S-wave velocities are trigonometrically weighted between fast and slow axial velocities. Averaging over a range of non-axial angles yields effective velocities as encountered by through-going crustal raypaths. Axial velocities cannot be simply used to quantify crustal anisotropic effects. The angular behavior of P-wave delay and shear wave splitting are sensitive to VP measured diagonal to the material symmetry axes; this diagonal velocity controls the presence or absence of non-axial shear wave singularities. These behavior help quantify the contributions of crustal rocks to observations of seismic anisotropy which can serve as proxies for crustal deformation.

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Abstract

Keywords
Seismology, Body wave propagation, Seismology, Theory and modeling, Seismology, Continental crust, Physical Properties of Rocks, Acoustic properties
Journal
Geophysical Research Letters
http://www.agu.org/journals/gl/
Publisher
American Geophysical Union
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