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Detailed Reference Information |
Nataf, H.-C., Nakanishi, I. and Anderson, D.L. (1984). Anisotropy and shear-velocity heterogeneities in the upper mantle. Geophysical Research Letters 11: doi: 10.1029/GL011i002p00109. issn: 0094-8276. |
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Long-period surface waves are used to map lateral heterogeneities of velocity and anisotropy in the upper mantle. The dispersion curves are expanded in spherical harmonics up to degree 6 and inverted to find the depth structure. The data are corrected for the effect of surface layers and both Love and Rayleigh waves are used. Shear wave velocity and shear polarization anisotropy can be resolved down to a depth of about 450 km. The sher wave velocity distribution to 200 km depth correlates with surface tectonics, except in a few anomalous regions. Below that depth the correlation vanishes. Cold subducted material shows up weakly at 350 km as fast S-wave anomalies. In the transition region a large scale pattern appears with fast mantle in the South-Atlantic. S-anisotropy at 200 km can resolve uprisinng or downwelling currents under some ridges and subduction zones. The Pacific shows a NW-SE fabric. |
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Publisher
American Geophysical Union 2000 Florida Avenue N.W. Washington, D.C. 20009-1277 USA 1-202-462-6900 1-202-328-0566 service@agu.org |
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