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The impact of lateral variations in lithospheric thickness on glacial isostatic adjustment in West Antarctica

Nield, G.A.; Whitehouse, P.L.; van der Wal, W.; Blank, B.; O'Donnell, J.P.; Stuart, G.W.

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W. van der Wal

B. Blank

J.P. O'Donnell

G.W. Stuart


Differences in predictions of Glacial Isostatic Adjustment (GIA) for Antarctica persist due to uncertainties in deglacial history and Earth rheology. The Earth models adopted in many GIA studies are defined by parameters that vary in the radial direction only and represent a global average Earth structure (referred to as 1D Earth models). Over-simplifying actual Earth structure leads to bias in model predictions in regions where Earth parameters differ significantly from the global average, such as West Antarctica. We investigate the impact of lateral variations in lithospheric thickness on GIA in Antarctica by carrying out two experiments that use different rheological approaches to define 3D Earth models that include spatial variations in lithospheric thickness. The first experiment defines an elastic lithosphere with spatial variations in thickness inferred from seismic studies. We compare the results from this 3D model with results derived from a 1D Earth model that has a uniform lithospheric thickness defined as the average of the 3D lithospheric thickness. Irrespective of deglacial history and sub-lithospheric mantle viscosity, we find higher gradients of present-day uplift rates (i.e. higher amplitude and shorter wavelength) in West Antarctica when using the 3D models, due to the thinner-than-1D-average lithosphere prevalent in this region. The second experiment uses seismically-inferred temperature as input to a power-law rheology thereby allowing the lithosphere to have a viscosity structure. Modelling the lithosphere with a power-law rheology results in behaviour that is equivalent to a thinner-lithosphere model, and it leads to higher amplitude and shorter wavelength deformation compared with the first experiment. We conclude that neglecting spatial variations in lithospheric thickness in GIA models will result in predictions of peak uplift and subsidence that are biased low in West Antarctica. This has important implications for ice-sheet modelling studies as the steeper gradients of uplift predicted from the more realistic 3D model may promote stability in marine-grounded regions of West Antarctica. Including lateral variations in lithospheric thickness, at least to the level of considering West and East Antarctica separately, is important for capturing short wavelength deformation and it has the potential to provide a better fit to GPS observations as well as an improved GIA correction for GRACE data.


Nield, G., Whitehouse, P., van der Wal, W., Blank, B., O'Donnell, J., & Stuart, G. (2018). The impact of lateral variations in lithospheric thickness on glacial isostatic adjustment in West Antarctica. Geophysical Journal International, 214(2), 811-824.

Journal Article Type Article
Acceptance Date Apr 17, 2018
Online Publication Date Apr 21, 2018
Publication Date Aug 1, 2018
Deposit Date Apr 26, 2018
Publicly Available Date Apr 27, 2018
Journal Geophysical Journal International
Print ISSN 0956-540X
Electronic ISSN 1365-246X
Publisher Oxford University Press
Peer Reviewed Peer Reviewed
Volume 214
Issue 2
Pages 811-824


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Copyright Statement
© The Author(s) 2018. Published by Oxford University Press on behalf of The Royal Astronomical Society.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.

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