The dynamical influences of a hard transition zone on post-glacial uplifts and rotational signatures

Recent investigations from laboratory and Monte-Carlo inversion of geophysical signatures have suggested that the transition zone of the mantle between 400 and 670 km depth may be stiffer than the lower and the upper mantle. By means of a five-layer viscoelastic spherical Earth model, we have calculated the displacement fields associated with post-glacial rebound, the induced polar motions, the temporal variations of the coefficients of the geopotential up to degree eight and the stress fields induced by deglaciation in the lithosphere and the upper mantle. Temporal variations of stress fields in the lithosphere reveal a non-monotonic behaviour due to the viscosity stratification. The results demonstrate the importance of the coming LAGEOS II geodetic satellite mission on constraining the rheological nature of the transition zone in the mantle. -from Authors