Multiscale model of global inner-core anisotropy induced by hcp-alloy plasticity
Abstract
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 equatorThe 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 \textless{}c+a\textgreater{} slip, and large-scale flow induced by a low-degree inner-core formation model. For global anisotropies ranging between 1 and 3%, the elastic anisotropy in the single crystal ranges from 5 to 20% with larger velocities along the c-axis.
Keywords
Cite
@article{arxiv.1601.05674,
title = {Multiscale model of global inner-core anisotropy induced by hcp-alloy plasticity},
author = {A Lincot and Ph Cardin and R Deguen and Sébastien Merkel},
journal= {arXiv preprint arXiv:1601.05674},
year = {2016}
}