Nonequilibrium phase boundaries in the earth's mantle

Deep seismic sounding in the earth's mantle has identified radial nonuniformities that are usually interpreted as zones of transition from one phase to another. A widely used technique is the modeling of phase boundaries in terms of strong discontinuities of the properties of the geological medium; at the discontinuity, the standard system of equations is supplemented by the classical Gibbs condition. We consider the blurred phase boundary with internal dissipation resulting from the nonequilibrium nature of the transition can change our theories of the effect of phase boundaries on the nature of convective flows in the mantle.