Glacial isostatic adjustment and post-seismic deformation in Antarctica

Wal, Wouter van der; Barletta, V; Nield, Grace; Calcar, Caroline van

doi:10.1144/m56-2022-13

Cited by 7 publications

(5 citation statements)

References 251 publications

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“…We also find that, for such low viscosities in the upper part of the upper mantle, we can get a better fit of geoid and dynamic topography, even if the density anomaly only extends to depth 350 km, approximately consistent with our geodynamic forward model results. As this viscosity range is still rather large and uncertain, we cannot provide an independent viscosity estimate, but at least lend support to other recent estimates (Ivins et al, 2022;van der Wal et al, 2022) which are similar or somewhat higher.…”

Section: Discussionsupporting

confidence: 74%

“…The presence of hot low-viscosity material has also been concluded by others (Ivins et al, 2022;van der Wal et al, 2022). Mostly, viscosity has been obtained by scaling seismic velocity perturbations (Kaufmann et al, 2005;A et al, 2012).…”

Section: Residual Topography (Figurementioning

confidence: 67%

“…Except in the context of glacial isostatic adjustment (van der Wal et al, 2022), there have been only a rather limited number of geodynamic models specifically about the mantle beneath (West) Antarctica. Seroussi et al (2017) study the influence of a West Antarctic mantle plume on ice sheet basal conditions and find that they have an important local impact, with basal melting rates reaching several centimeters per year directly above the hotspot.…”

Section: Residual Topography (Figurementioning

confidence: 99%

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Exploring the Origin of Geoid Low and Topography High in West Antarctica: Insights from Density Anomalies and Mantle Convection Models

Steinberger,

Grasnick,

Ludwig

2023

tekt

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The deepest geoid low globally with respect to hydrostatic equilibrium is in the Ross Sea area. Nearby in West Antarctica is a residual topography high. Both are in a region with thin lithosphere, where a mantle plume has been suggested. Hence upper mantle viscosity could be regionally reduced, allowing for faster rebound than elsewhere upon melting of the West Antarctic Ice Sheet, one of the global climate system’s tipping elements. To study possible causes of the geoid low / topography high combination, we compute the effects of disk-shaped density anomalies. With -1% density anomaly and a global average radial viscosity structure, geoid low and topography high can be explained with disk radius about 10° and depth range ~150-650 km. Alternatively, there may be two separate disks somewhat laterally displaced, one just below the lithosphere and mainly causing a dynamic topography high and one below the transition zone causing the geoid low. If viscosity in the uppermost mantle is reduced by a factor 10 (from 50 to 350 km depth) to 100 (from 100 to 220 km), one shallow disk in the depth range 50-350 km would also be sufficient. In order to test the feasibility of such density models, we perform computations of a thermal plume that enters at the base of a cartesian box corresponding to a region in the upper mantle, as well as some whole-mantle thermal plume models, with ASPECT. These plume models have typically a narrow conduit and the plume tends to only become wider as it spreads beneath the lithosphere, typically shallower than ~300 km. These results are most consistent with the shallow disk model with reduced uppermost mantle viscosity, hence providing further support for such low viscosities beneath West Antarctica.

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Section: Discussionsupporting

confidence: 74%

Section: Residual Topography (Figurementioning

confidence: 67%

Section: Residual Topography (Figurementioning

confidence: 99%

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Exploring the Origin of Geoid Low and Topography High in West Antarctica: Insights from Density Anomalies and Mantle Convection Models

Steinberger,

Grasnick,

Ludwig

2023

tekt

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“…Viscosity maps as input for GIA modelling are reviewed in van der Wal et al (2022). The history of GIA research, GIA observations, modelling techniques, and interactions between GIA and the solid Earth are discussed.…”

Section: Influence On Icementioning

confidence: 99%

An introduction to the geochemistry and geophysics of the Antarctic mantle

Martin

Wal

Boer

2022

Memoirs

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The Antarctic mantle, bounded between the core and the Mohorovičić discontinuity, is one of the most difficult targets of study on Earth because of ice cover and rare outcrop. A multidisciplinary approach is adopted in this volume, using petrology, geochemistry, remote sensed data and geodesy, to characterise the Antarctic mantle. This characterisation has application to rates of glacial isostatic adjustment, heat flow, sea level rise and tectonics. It places the Antarctic mantle domain in a global framework on a scale not attempted before. In this chapter we review the historical development of mantle studies in Antarctica, outline current research directions, introduce the volume chapters and provide a summary and outlook.

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“…For a full summary on the topic in an Antarctic context, the reader is referred to van der Wal et al. (2023).…”

Section: Introductionmentioning

confidence: 99%

Postseismic Deformation in the Northern Antarctic Peninsula Following the 2003 and 2013 Scotia Sea Earthquakes

Nield,

King,

Koulali

et al. 2023

JGR Solid Earth

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Large earthquakes in the vicinity of Antarctica have the potential to cause postseismic viscoelastic deformation affecting measurements of displacement that are used to constrain models of glacial isostatic adjustment (GIA). In November 2013, a Mw 7.7 strike‐slip earthquake occurred in the Scotia Sea, 650 km from the Antarctic Peninsula. GPS time series from the northern Peninsula show a change in rate after this event, indicating a far‐field postseismic deformation signal is present. In this study, we use a finite element model with a suite of 1D and 3D Earth structures to investigate the extent of postseismic deformation in the Antarctic Peninsula. Model output is compared with GPS time series to place constraints on the Earth structure in this region. The preferred Earth structure has a thin lithosphere combined with a Burgers rheology with steady‐state viscosity of 4 × 1018 Pa s and transient viscosity one order of magnitude lower. Our study shows that including 3D Earth structure does not improve the fit. Using the best fitting Earth structure, we run a forward model of the nearby 2003 Mw 7.6 strike‐slip earthquake and combine the predictions for both earthquakes. We show that postseismic deformation is widespread across the northern Peninsula with rates of horizontal deformation up to 1.65 mm/yr for the period 2015–2020, a signal that persists for decades. These results suggest that much of Antarctica may be deforming due to recent postseismic deformation and this signal needs to be accounted for when using GPS observations to constrain geophysical models.

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Glacial isostatic adjustment and post-seismic deformation in Antarctica

Cited by 7 publications

References 251 publications

Exploring the Origin of Geoid Low and Topography High in West Antarctica: Insights from Density Anomalies and Mantle Convection Models

Exploring the Origin of Geoid Low and Topography High in West Antarctica: Insights from Density Anomalies and Mantle Convection Models

An introduction to the geochemistry and geophysics of the Antarctic mantle

Postseismic Deformation in the Northern Antarctic Peninsula Following the 2003 and 2013 Scotia Sea Earthquakes

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