On the viscosity and creep mechanism of Earth's inner core
Article first published online: 28 OCT 2004
Copyright 2004 by the American Geophysical Union.
Geophysical Research Letters
Volume 31, Issue 20, October 2004
How to Cite
2004), On the viscosity and creep mechanism of Earth's inner core, Geophys. Res. Lett., 31, L20606, doi:10.1029/2004GL021209.(
- Issue published online: 28 OCT 2004
- Article first published online: 28 OCT 2004
- Manuscript Accepted: 8 OCT 2004
- Manuscript Revised: 4 OCT 2004
- Manuscript Received: 5 AUG 2004
 The viscosity and creep mechanism of Earth's inner core are evaluated based on microphysical models of the flow properties of iron under high pressure and temperature, low stress and large grain size. Harper-Dorn creep, a Newtonian-viscous dislocation mechanism, is shown to be the likely deformation process, and the viscosity is predicted to be ∼1011 Pa s, at the low end of previous estimates. Such a low viscosity implies that the inner core can adjust its shape to maintain alignment with the gravitational field imposed by the mantle on a timescale of approximately one minute. It also implies that strain sufficient to produce significant lattice preferred orientation could develop in a few years to a few hundred years, which suggests that seismic anisotropy of the inner core is the product of active deformation and has no memory of primary crystallization.