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Science 10 December 1993:
Vol. 262. no. 5140, pp. 1708 - 1711
DOI: 10.1126/science.262.5140.1708
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Articles

Inner Core Anisotropy Due to the Magnetic Field—induced Preferred Orientation of Iron

Shun-ichiro Karato 1

1 Department of Geology and Geophysics, University of Minnesota, Minneapolis, MN 55455

Anisotropy of the inner core of the Earth is proposed to result from the lattice preferred orientation of anisotropic iron crystals during their solidification in the presence of a magnetic field. The resultant seismic anisotropy is related to the geometry of the magnetic field in the core. This hypothesis implies that the observed anisotropy (fast velocity along the rotation axis) indicates a strong toroidal field in the core, which supports a strong field model for the geodynamo if the inner core is made of hexagonal close-packed iron.

Submitted on July 13, 1993
Accepted on October 7, 1993


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