Abstract
<p> The Antarctic Ice Sheet (AIS) is the largest ice sheet on Earth that has known important mass <br> changes during the last 20 kyrs. These changes deform the Earth and modify its gravity field, <br> a process known as Glacial Isostatic Adjustment (GIA). GIA is directly influenced by the mechanical<br> properties and internal structure of the Earth, and is monitored using Global Navigation Satellite <br> System positioning or gravity measurements. However, GIA in Antarctica remains poorly constrained  <br> due to the cumulative effect of past and present ice-mass changes, the unknown history of the past<br> ice-mass change, and the uncertainties of the mechanical properties of the Earth. The viscous <br> deformation due to GIA is usually modeled using a Maxwell rheology. However, other geophysical<br> processes employ Andrade (tidal deformation) or Burgers (post-seismic deformation) laws that could <br> result in a more rapid response of the Earth. We investigate the effect of using these<br> different rheology laws to model GIA-induced deformation in Antarctica.  </p><p>Employing the ALMA and TABOO softwares, we use the Love number and Green functions formalism to <br>compute the surface motion and the gravity changes induced by the past and present ice-mass redistributions. <br>We use the elastic properties and the radial structure of the preliminary reference Earth model (PREM) and the <br>viscosity profile given by Hanyk (1999). The deformation is computed for the three rheological laws mentioned <br>above using ICE-6G and elevation changes from ENVISAT (2002-2010) to represent the past and present changes<br>of the AIS, respectively. </p><p>We obtain that the three rheological laws lead to significant Earth response within a 20 kyrs time interval since <br>the beginning of the ice-mass change. The differences are the largest between Maxwell and Burgers rheologies <br>during the 500 years following the beginning of the surface-mass change. Regarding the response to present <br>changes in Antarctica, the largest discrepancies are obtained in regions with the greatest current melting rates, <br>namely Thwaites and Pine Island Glacier in West Antarctica. Uplift rates computed twelve years after the end of<br>the present melting using Burgers and Andrade rheologies are five and two times larger than those obtained <br>using Maxwell, respectively. </p>
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