Abstract
Since 1995 several ice shelves in the Northern Antarctic Peninsula have collapsed and triggered ice-mass unloading, invoking a solid Earth response that has been recorded at continuous GPS (cGPS) stations. A previous attempt to model the observation of rapid uplift following the 2002 breakup of Larsen B Ice Shelf was limited by incomplete knowledge of the pattern of ice unloading and possibly the assumption of an elastic-only mechanism. We make use of a new high resolution dataset of ice elevation change that captures ice-mass loss north of 66°S to first show that non-linear uplift of the Palmer cGPS station since 2002 cannot be explained by elastic deformation alone. We apply a viscoelastic model with linear Maxwell rheology to predict uplift since 1995 and test the fit to the Palmer cGPS time series, finding a well constrained upper mantle viscosity but less sensitivity to lithospheric thickness. We further constrain the best fitting Earth model by including six cGPS stations deployed after 2009 (the LARISSA network), with vertical velocities in the range 1.7 to 14.9 mm/yr. This results in a best fitting Earth model with lithospheric thickness of 100–140 km and upper mantle viscosity of 6×1017–2×1018 Pas – much lower than previously suggested for this region. Combining the LARISSA time series with the Palmer cGPS time series offers a rare opportunity to study the time-evolution of the low-viscosity solid Earth response to a well-captured ice unloading event.
Highlights
Rapid changes in climate in the Antarctic Peninsula (AP) over the past 50 years have led to the retreat and eventual collapse of several major ice shelves (Fig. 1), such as Prince Gustav by 1993–1995 (Rott et al, 1996), Larsen A in 1995 (Rott et al, 1996), and Larsen B in 2002 (Rack and Rott, 2004) (see Cook and Vaughan (2010) for a complete summary)
The study of Thomas et al (2011) identified markedly-increased uplift in GPS coordinate time series from the Northern Antarctic Peninsula (NAP) that they associated with ice unloading related to the breakup of Larsen B Ice Shelf in 2002
Using the ice-mass change dataset and observations from seven continuous GPS (cGPS) stations we have been able to constrain a range of Earth models for the NAP
Summary
Rapid changes in climate in the Antarctic Peninsula (AP) over the past 50 years have led to the retreat and eventual collapse of several major ice shelves (Fig. 1), such as Prince Gustav by 1993–1995 (Rott et al, 1996), Larsen A in 1995 (Rott et al, 1996), and Larsen B in 2002 (Rack and Rott, 2004) (see Cook and Vaughan (2010) for a complete summary). The study of Thomas et al (2011) identified markedly-increased uplift in GPS coordinate time series from the Northern Antarctic Peninsula (NAP) that they associated with ice unloading related to the breakup of Larsen B Ice Shelf in 2002 This uplift was best captured in the near-continuous cGPS record at Palmer station which exhibited an increase in uplift rate from 0.1 mm/yr prior to 2002.2, to 8.8 mm/yr thereafter. Due to the active tectonic setting of the region, the mantle is likely to have a relatively low viscosity compared with other locations undergoing deformation in response to changes in ice-mass e.g. East Antarctica or Fennoscandia. All model-predicted uplift rates were estimated over the same time period as the cGPS observed uplift rate
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
