Inner Core Dynamics

This chapter reviews current understanding of the dynamical processes occurring in the inner core, motivated primarily by seismological inferences. First, we present a review of the basics needed for modeling, namely, the physical properties of the iron alloy that constitutes the core, the physics of solidifying alloys, and the grain size and rheology of the inner core. Using these constraints, we review critically the various models that have been proposed to explain seismic velocity, elastic anisotropy, attenuation and attenuation anisotropy, and their radial and lateral variations in the inner core. Finally, we present a review of the models proposed to explain inner core rotation, inferred to exist from the secular changes in seismic velocity in the inner core, and inner core translation, suggested to explain simultaneously lateral variations in the inner core and a layer at the base of the outer core that shows a decrease in the P-wave velocity gradient.