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Inner-core anisotropy and rotation

Tromp­, Jeroen (2001) Inner-core anisotropy and rotation. Annual Review of Earth and Planetary Sciences, 29 . pp. 47-69. ISSN 0084-6597. http://resolver.caltech.edu/CaltechAUTHORS:TROareps01

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Abstract

This paper reviews recent research focused on the Earth's inner core. Large inner-core traveltime anomalies and the anomalous splitting of core-sensitive free oscillations strongly suggest that the inner core is anisotropic. Initial models involved a simple, constant or depth-dependent cylindrical anisotropy at a level less than a few percent. Recent observations suggest that its eastern hemisphere is largely isotropic, whereas its western hemisphere is highly anisotropic, and there are indications that its top 100 km may be isotropic. The coda of inner-core reflected phases has been used to infer strong heterogeneities with a length scale of just a few kilometers. Thus, a complicated three-dimensional picture of the inner core is beginning to emerge, although it has been suggested that much of this complexity may be the misinterpretation of signals that have their origin in the lowermost mantle. Numerical models of the geodynamo suggest that the inner core may rotate at a slightly different rate than the mantle. Recent seismological estimates based upon traveltime and normal-mode data limit inner-core differential rotation to less than +0.2 degrees per year.


Item Type:Article
Additional Information:"Reprinted, with permission, from the Annual Review of Earth and Planetary Sciences, Volume 29 copyright 2001 by Annual Reviews, www.annualreviews.org" I thank Joe Durek, Miaki Ishii, Gabi Laske, and Xiaodong Song for providing some of the figures for this paper.
Subject Keywords:SEISMOLOGY OF THE CORE; INNER-CORE BOUNDARY; INNER-CORE SHEAR WAVES; INNER-CORE VISCOSITY; INNER-CORE ATTENUATION; DIFFERENTIAL TRAVEL-TIMES; FREE-OSCILLATION SPECTRA; EARTHS OUTER CORE; HIGH-PRESSURE; ASPHERICAL STRUCTURE; SCALE HETEROGENEITY; NORMAL-MODES; SEISMOLOGICAL CONSTRAINTS; SEISMIC ANISOTROPY; ELASTIC-ANISOTROPY
Record Number:CaltechAUTHORS:TROareps01
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:TROareps01
Alternative URL:http://dx.doi.org/10.1146/annurev.earth.29.1.47
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:1640
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:08 Feb 2006
Last Modified:26 Dec 2012 08:45

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