Surface-wave propagation in an ocean basin with an anisotropic upper mantle: observations of polarization anomalies |
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Authors: | S. C. Kirkwood Stuart Crampin |
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Affiliation: | Department of Geophysics, University of Edinburgh, James Clerk Maxwell Building, Edinburgh EH9 3JZ;Institute of Geological Sciences, Murchison House, West Mains Road, Edinburgh EH9 3LA |
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Abstract: | Summary. Observations of surface waves crossing ocean basins indicate that, at least in some cases, a better interpretation of what was previously considered to be the simultaneous arrival of fundamental Love and second Rayleigh modes, with similar group velocities, is the coupled motion of the second-generalized mode surface wave propagating in an anisotropic upper-mantle. This mode displays the polarization anomalies expected from anisotropic alignments caused by syntectonic recrystallization of olivine in a zone of horizontal shear. The polarity of the pattern of anomalies, found in waves crossing the Pacific Basin, suggests that the lithosphere is dragging the asthenosphere. |
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