DI33A-2620
A Multi-scale Self-consistent Model of Earth’s Inner Core Anisotropy
Wednesday, 16 December 2015
Poster Hall (Moscone South)
Philippe Cardin, ISTerre Institut des Sciences de la Terre, UGA - CNRS, Grenoble, France, Sebastien Merkel, Université de Lille, Villeneuve d'Ascq, France, Ainhoa Lincot, University Joseph Fourier Grenoble, Grenboble, France and Renaud Deguen, LGLTPE Laboratoire de Géologie de Lyon : Terre, Planètes et Environnement, Villeurbanne Cedex, France; Université Claude Bernard, Laboratoire de Géologie de Lyon, Lyon, France
Abstract:
The Earth’s solid inner-core exhibits global seismic anisotropy resulting from a coherent alignment of anisotropic Fe-alloy through the inner-core history that can be sampled at the global scale of present-day seismic observations. By combining self-consistent polycrystal plasticity, inner-core formation models, and simulations of seismic measurements, we introduce a multi-scale self-consistent model that can reproduce observations of global seismic anisotropy of several percents and aligned with the Earth’s rotation axis. Necessary conditions for such model are an hexagonal-close-packed structure for the inner core Fe-alloy, 20% elastic anisotropy in the single crystal, plastic deformation by pyramidal slip, and large-scale flow induced by a low-degree inner-core formation model. Our approach allows using seismic anisotropy as a proxy for the formation and tectonics of the deepest portions of the planet.
