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Abstract

Glacial-isotactic adjustment (GIA) is one of the key processes considering relative sea-level (RSL) and paleo-topography during the last glacial cycle. Especially in former ice-covered regions the subsidence of the solid Earth due to ice loads can reach more than 500 m and contributes to the stability of ice-sheets (e.g. position of grounding line and ice-sheet elevation), whereas at the coasts of the world oceans the deformation is governed by global RSL fall of more than 100 m. Because the viscoelastic response of the solid Earth is governed by its viscosity structure, the effect of lateral viscosity variations on deformations due to GIA has to be estimated. The importance was already shown for the differences in earth structure below the glacial ice sheets of Fennoscandia and Laurentide, as well as for a number of peripheral and far-field regions. One open question arises: Can the 3D earth properly be parameterized by locally optimized 1D earth structures? In this study, we apply a 3D Earth structure which we derived from seismic tomography and further geodynamic constraints as an a priori estimation of the Earth viscosity distribution. Applying a standard glaciation history, we compare the response characteristics of 1D and 3D earth parameterizations and discuss the limits of optimized 1D earth parametrizations. We will focus on reconstructions of RSL during the last deglaciation in view of sea level index points which are generally used for validating the GIA process.