Sea-level changes, geoid and gravity anomalies due to Pleistocene deglaciation by means of multilayered, analytical Earth models

A new class of analytical, multilayered, viscoelastic Earth models based on the seismic model PREM (Dziewonski and Anderson, 1981), with an incompress ible, linear, viscoelastic Maxwell rheology, is applied to the modeling of global sea-level changes due to Pleistocene deglaciation. Until now, analyt ical schemes based on normal mode theory, have dealt with at most five laye rs, an elastic lithosphere, a three layered mantle including a transition z one, and a core (Spada et al., 1992; Geophys. J. Int. 109, 683-700). The no velty of our approach, used for the first time in sealevel studies, stands on an analytical scheme that can reproduce continuous elastic and rheologic al stratification when a sufficient number of layers is taken into account. We specifically assess the importance of our results for the Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) satellite mission. GOCE will resolve the gravity field with a spatial resolution (half-wavelength) of 75 km and amplitude of 1.5 mgal, with a uniform coverage over the Earth , including presently unsurveyed, remote areas. Our models lead to post-gla cial rebound induced free air gravity anomalies of a few mgals peak-to-peak in the harmonic degree range l=80-200, which will be discernible by GOCE. This finding demonstrates that post-glacial rebound has a high frequency co mponent in the gravity field that can in principle be resolved by high reso lution gravity satellite missions. We show that post-glacial rebound can co ntribute a substantial fraction to present-day sea-level Variations and poi nt out that for the Mediterranean Sea they are of the same order of magnitu de as those induced by tectonic processes. (C) 2000 Elsevier Science B.V. A ll rights reserved.