Impact of the Icelandic hotspot on GPS time series in southeast Greenland

The mass lost from Greenland ice sheet is one of the most important contribution to the global sea level rise, and it is under constant monitoring. However, still little is known about the heat flux at the glacier bedrock, and how it affects dynamics of the major outlet glaciers in Greenland. Recent studies suggest that the hotspot currently under Iceland have been under eastern Greenland at ~40 Ma BP and that the upwelling of hot material from the Iceland plume towards Greenland is ongoing. A warm upper mantle has a low viscosity, which in turn causes the solid Earth to rebound much faster to deglaciation. We have good reasons to believe that mantle beneath SE-Greenland has very low viscosity (Khan, et al. 2016), as also suggested by the discrepancy between the GPS velocities and the predicted purely elastic deformations caused by present-day ice loss. Here we present a preliminary computation of the Earth deformation driven by a low viscosity mantle excited by the deglatiation since the little ice age (LIA) to the present day. We produce the time series of such deformation and compare it with GPS time series, the oldest dating back to 1992.