Multiscale model of global inner-core anisotropy induced by hcp-alloy plasticity
Résumé
• Multiscale model of inner-core anisotropy produced by hcp alloy deformation
• 5 to 20% single-crystal elastic anisotropy and plastic deformation by pyramidal slip
• Low-degree inner-core formation model with faster crystallization at the equator
The Earth's solid inner-core exhibits a global seismic anisotropy of several percents. It results from a coherent alignment of anisotropic Fe-alloy crystals through the inner-core history that can be sampled by present-day seismic observations. By combining self-consistent polycrystal plasticity, inner-core formation models, Monte-Carlo search for elastic moduli, and simulations of seismic measurements, we introduce a multiscale model that can reproduce a global seismic anisotropy of several percents aligned with the Earth's rotation axis. Conditions for a successful model are an hexagonal-close-packed structure for the inner-core Fe-alloy, plastic deformation by pyramidal
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