Calculation of the Electrical Resistivity of Liquid Iron in the Earth's Core

Abstract

SEVERAL empirical values for the electrical resistivity of the Earth's fluid core have been proposed1. The latest estimates are those of Gardiner and Stacey2 which correct earlier estimates by Stacey3. They use data on the electrical resistivity and its temperature coefficient for liquid iron and its alloys at 1,800 K and combine this with the observed pressure coefficient of resistivity in solid iron-nickel alloys at 100 kbar. These results are then extrapolated to the core temperatures (∼ 4,000 K) and pressures (3,000 kbar) assuming the temperature and pressure effects to be additive. As the authors of ref. 2 admit, this latter assumption is of doubtful validity. Obviously such large extrapolations involve considerable uncertainties; since the core resistivity is a vital parameter in the theories of the origin of the geomagnetic field it is important to assess the validity of the existing estimates.