Deformation of earth's inner core by electromagnetic forces

A recent study of Karate (1999) suggests that deformation induced in the in ner core by electromagnetic (Lorentz) forces may account for the developmen t of seismic anisotropy. The viability of this proposal depends on whether Lorentz forces can sustain persistent flow within the inner core. We explor e this question by establishing the conditions for static equilibrium when Lorentz forces are present. We find that the requirements for thermodynamic and hydrostatic equilibrium are incompatible at the surface of the inner c ore. However, the resulting deformation redistributes mass in the interior so as to minimize steady flow. Numerical calculations show that the flow be comes vanishingly weak and is confined to the top of the inner core. Strain s in the interior are small and the alignment of crystals is insufficient t o explain the anisotropy inferred from seismological observations.