Convection and anisotropy of the inner core



Estimation of the Rayleigh number of the inner core suggests that this region is convecting. The flow pattern is likely to produce crystallographic preferred orientation of the elastically anisotropic hexagonal closest packed (ϵ) phase of iron, such that compressional-wave velocities would be greater in the axial relative to the equatorial direction by roughly 1 percent. This result is in agreement with seismological evidence that the inner core is elastically anisotropic.