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Science 24 January 2003:
Vol. 299. no. 5606, pp. 552 - 555
DOI: 10.1126/science.1078159
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Reports
Robust Normal Mode Constraints on Inner-Core Anisotropy from Model Space Search
Caroline Beghein,*
Jeannot Trampert
A technique for searching full model space that was applied to
measurements of anomalously split normal modes showed a robust pattern
of P-wave and S-wave anisotropy in the inner
core. The parameter describing P-wave anisotropy changes
sign around a radius of 400 kilometers, whereas S-wave
anisotropy is small in the upper two-thirds of the inner core and
becomes negative at greater depths. Our results agree with observed
travel-time anomalies of rays traveling at epicentral distances varying
from 150° to 180°. The models may be explained by progressively
tilted hexagonal close-packed iron in the upper half of the inner core
and could suggest a different iron phase in the center.
Faculty of Earth Sciences, Utrecht University, Post Office Box
80021, 3508 TA Utrecht, Netherlands.
*
To whom correspondence should be addressed. E-mail:
beghein{at}geo.uu.nl
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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
- Elastic Anisotropy of Earth's Inner Core.
- A. B. Belonoshko, N. V. Skorodumova, A. Rosengren, and B. Johansson (2008)
Science
319, 797-800
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