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| Titel |
Intrinsic versus extrinsic seismic anisotropy-The case of the Preliminary Reference Earth Model (PREM) |
| VerfasserIn |
Nian Wang, Jean-Paul Montagner, Andreas Fichtner, Yann Capdeville |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250074777
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| Zusammenfassung |
| Seismic anisotropy is necessary for explaining different kinds of seismic and mineralogical
data and provides invaluable information on geodynamics and rheology of the earth.
However, its interpretation is difficult and non-unique because the observed anisotropy is
due to different mechanisms, and is usually a mixture of intrinsic and extrinsic
(artificial) anisotropies at all physical length scales. Anisotropy may result from
the lattice or crystallographic preferred orientation (L.P.O., C.P.O.), from shape
preferred orientation (S.P.O.) produced by alignment of micro-cracks with and
without fluid inclusions, or from fine layering. Here we give a thorough analysis
of anisotropy introduced by fine layering, including discussions on the effective
elastic constants of a characteristic finely layered isotropic model which is called the
periodic, isotropic, two layered (PITL) model, together with the amplitude of the
associated radial artificial anisotropy. We also explore the possibility of the PITL model
explaining the radial anisotropy in the PREM, and find that the fine layering can
explain part of the observed anisotropy in the lithosphere, whereas the anisotropy
in the asthenosphere is more relate to the intrinsic anisotropy or partial melting. |
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