3D Postglacial Rebound With Lateral Rheological Heterogeneities

We study the Earth response to the melting of the Pleistocene ice sheets by a numerical 3D FE approach. Starting from a reference spherically symmetric Earth model, which has been successfully benchmarked with available solutions based on the viscoelastic normal modes, we include laterally varying structures to discriminate which kind of heterogeneities can be revealed by relative sealevel and geodetic datasets. We focus on the lateral variations in the lithosphere and upper mantle, and we assume a viscoelastic Maxwell linear rheology in all of our computations. In the lithosphere we include a global regionalization which accounts for oceanic, continental and cratonic provinces, whereas in the upper mantle the main feature studied is a low-viscosity region beneath the oceanic plates. Since a high-resolution analysis is not possible due to the huge computer requirements of the FE model, our present analysis is adequate to the study of the effects of the long-wavelength mantle heterogeneities. Our preliminary results suggests that the departure from the spherical symmetry can affect both the predicted relative sealevel curves and the present-day rates of deformation measured by geodetic methods.