| The 410 and 660 km seismic discontinuities are generally believed to be caused by phase transitions of mantle minerals. If the material near these discontinuities can change phase in response to changes in temperature and pressure associated with geodynamical or seismic processes, then these processes will be affected. While models of convective processes account for these phase transitions, many processes at shorter time scales, such as post-glacial rebound and seismic normal modes, do not.;In this thesis, I model the effect of these phase transitions on post-glacial rebound, seismic normal modes, and downwelling mantle material. I have developed a method for including phase boundary conditions into the formalism of these geophysical processes that allows for conduction of latent heat away from the boundary. Ignoring latent heat in the case of post-glacial rebound, the buoyancy modes associated with these boundaries become geostrophic modes. Comparing to results assuming chemical boundaries, the elastic load love numbers change by up to a factor of three for low degrees, and surface observations are changed by up to 30%. Including latent heat, the surface observations are still affected on the 10% level. This effect is increased if the latent heat is released over a thick boundary. Overall, failure to include phase boundary conditions will result in an approximate 20% error in viscosity profile determination.;Without latent heat release, seismic normal mode frequencies can be changed by phase boundary conditions on the 2% level, far greater than the uncertainties in measurement. However, latent heat release eliminates the effect for a thin boundary. In general, the phase boundary does not respond to sinusoidal forcing on time scales shorter than those of post-glacial rebound unless the heat is released over a thick boundary. However, even for a thick boundary the kinetics of the transitions will likely prevent the phase changes for small amplitude motions, such as normal modes. |
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