Lopsided Growth of Earth's Inner Core

Hemispherical asymmetry is a prominent feature of Earth's inner core, but how this asymmetry relates to core growth is unknown. Based on multiple-scattering modeling of seismic velocity and attenuation measurements sampling the whole uppermost inner core, we propose that the growth of the solid...

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Bibliographic Details
Published in:Science (American Association for the Advancement of Science) 2010-05, Vol.328 (5981), p.1014-1017
Main Authors: Monnereau, Marc, Calvet, Marie, Margerin, Ludovic, Souriau, Annie
Format: Article
Language:English
Subjects:
Asymmetry
Attenuation
Convection
Crystallization
Earth
Earth Sciences
Earth, ocean, space
Earthquakes, seismology
Eastern hemisphere
Exact sciences and technology
Geology
Geophysics
Grain size
Inner cores
Internal geophysics
Melting
Outer cores
Sampling
Sciences of the Universe
Seismology
Skewed distributions
Solid-earth geophysics, tectonophysics, gravimetry
Translational motion
Translations
Velocity
Western hemisphere
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Summary:Hemispherical asymmetry is a prominent feature of Earth's inner core, but how this asymmetry relates to core growth is unknown. Based on multiple-scattering modeling of seismic velocity and attenuation measurements sampling the whole uppermost inner core, we propose that the growth of the solid core implies an eastward drift of the material, driven by crystallization in the Western Hemisphere and melting in the Eastern Hemisphere. This self-sustained translational motion generates an asymmetric distribution of sizes of iron crystals, which grow during their translation. The invoked dynamical process is still active today, which supports the idea of a young inner core.
ISSN:0036-8075
1095-9203
DOI:10.1126/science.1186212