Sharp hemisphere boundaries in a translating inner core

Geballe, Z. M. and Lasbleis, M. and Cormier, V. F. and Day, E. A. (2013) Sharp hemisphere boundaries in a translating inner core. Geophysical Research Letters, 40 (9). pp. 1719-1723. ISSN 00948276 DOI 10.1002/grl.50372

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Abstract

[1] Geodynamic models of a convectively translating inner core have recently been proposed that would account for the seismically observed differences in isotropic velocity between the eastern and western hemispheres of the inner core. These models, however, have previously been thought to be incompatible with seismic observations of a 1.5% P wave velocity change occurring over an 800 km wide region at the boundary between hemispheres of the inner core. Here we show that if rigid translation occurs, the age of material in the 100 km below the inner core boundary changes quickly as it crosses the boundary between the western and eastern hemispheres. We then forward model seismic traveltimes to show that the sharp transition in VP between hemispheres may be explained by a random distribution of highly oriented crystalline domains that grow during translation and are composed of material with relatively high elastic anisotropy (up to 12%).

Item Type: Article
Uncontrolled Keywords: NIL AREP
Subjects: 05 - Petrology - Igneous, Metamorphic and Volcanic Studies
Divisions: 02 - Geodynamics, Geophysics and Tectonics
Journal or Publication Title: Geophysical Research Letters
Volume: 40
Page Range: pp. 1719-1723
Identification Number: 10.1002/grl.50372
Depositing User: Sarah Humbert
Date Deposited: 16 May 2014 12:31
Last Modified: 16 May 2014 12:31
URI: http://eprints.esc.cam.ac.uk/id/eprint/3051

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