Low viscosity of the Earth’s inner core

Nature Communications. 2019. Vol. 10. No. 1. P. 1–7.

Belonoshko Anatoly B., Fu J., Bryk T., Simak S., Mattesini M.

The Earth’s solid inner core is a highly attenuating medium. It consists mainly of iron. The high attenuation of sound wave propagation in the inner core is at odds with the widely accepted paradigm of hexagonal close-packed phase stability under inner core conditions, because sound waves propagate through the hexagonal iron without energy dissipation. Here we show by first-principles molecular dynamics that the body-centered cubic phase of iron, recently demonstrated to be thermodynamically stable under the inner core conditions, is considerably less elastic than the hexagonal phase. Being a crystalline phase, the body-centered cubic phase of iron possesses the viscosity close to that of a liquid iron. The high attenuation of sound in the inner core is due to the unique diffusion characteristic of the body-centered cubic phase. The low viscosity of iron in the inner core enables the convection and resolves a …

Keywords: viscosity, iron, molecular dynamics, High pressure, mineral physics, Earth Core