Crustal seismic anisotropy in central Tibet: Implications for deformational style and flow in the crust

Receiver functions obtained at INDEPTH III stations located near the Bangong‐Nujiang suture in central Tibet display a weak Moho signal and strong P to S conversions within the first 5 s that vary systematically with back‐azimuth. A single station with representative azimuthal variations located at...

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Bibliographic Details
Published in:Geophysical research letters 2004-12, Vol.31 (23), p.L23601.1-n/a
Main Authors: Ozacar, A. Arda, Zandt, George
Format: Article
Language:English
Subjects:
Earth sciences
Earth, ocean, space
Exact sciences and technology
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Summary:Receiver functions obtained at INDEPTH III stations located near the Bangong‐Nujiang suture in central Tibet display a weak Moho signal and strong P to S conversions within the first 5 s that vary systematically with back‐azimuth. A single station with representative azimuthal variations located at the sharp onset of strong SKS splitting, is modeled for both dipping layers and seismic anisotropy by using a global minimization technique. Inversion results indicate strong anisotropy (>10%) near the surface and in the middle crust separated by a south‐dipping (∼25°) layer, possibly related to the earlier phase of crustal shortening. Near‐surface anisotropy has a fabric dipping steeply southward and trending WNW‐ESE that correlates with the suture and younger strike‐slip faults. In contrast, mid‐crustal anisotropy occurs in a low‐velocity zone and has a fabric dipping gently (∼18°) northward that might be related to a well‐developed near‐horizontal rock fabric induced by crustal flow.
ISSN:0094-8276
1944-8007
DOI:10.1029/2004GL021096