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Seismic anisotropy in the D″ layer
Author(s) -
Vinnik Lev,
Romanowicz Barbara,
Le Stunff Yves,
Makeyeva Larissa
Publication year - 1995
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/95gl01327
Subject(s) - geology , anisotropy , isotropy , diffraction , geodesy , seismology , physics , optics
We present observations of diffracted SV (SVd) for a path between the Fiji‐Tonga islands and the eastern coast of North America at distances greater than 110°. Observed features of S diffracted suggest that coupling between SVd and SHd can be ruled out as a first order effect for this path. Arrivals of SHd are late relative to IASP91 travel‐times by about 10 s, and those of SVd are late relative to SHd by 3 s, for most records. The slope of the log(SVd/SHd) spectral ratio is around 3 Hz −1 in the range 0.06–0.15 Hz . A transversely isotropic low‐velocity layer in the lower‐most mantle with a thickness of 200–300 km may account for most of the observed properties of SVd.