Influence of ice loading and earth properties on horizontal GPS motions in the Ross Sea region, Antarctica

Poster (2022)

Authors

Stephanie Ann Konfal Ohio State University
Terry J Wilson Ohio State University
Pippa L. Whitehouse Durham University
Grace A. Nield Durham University
Michael G Bevis Ohio State University
Tim Hermans NIOZ Royal Netherlands Institute for Sea Research
W. van der Wal Astrodynamics & Space Missions - Aerospace Engineering
Research Group
Astrodynamics & Space Missions (Aerospace Engineering) (TU Delft)
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Published Date

2022

Language

English

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Faculty

Aerospace Engineering

Department

Space Engineering

Research Group

Astrodynamics & Space Missions

Abstract

ANET-POLENET (Antarctic Network of the Polar Earth Observing Network)
bedrock GPS sites in the Ross Sea region of Antarctica are in close
proximity to a major LGM load center in the Siple region, and therefore
are thought to reflect motion due to GIA. For the simplest case,
horizontal bedrock motion is expected in a radial pattern away from the
former load, yet we instead observe three primary patterns of
deformation; 1) motions are reversed towards the load in the southern
region of the Transantarctic Mountains (TAM), 2) motions are radially
away from the load in the Marie Byrd Land (MBL) region, and 3) an
overall gradient in motion is present, with magnitudes progressively
increasing from East to West Antarctica. We aim to understand these
distinct patterns of horizontal bedrock motion and the causal sources of
deformation by investigating alternative earth models and ice loading
scenarios, with the goal of improving our understanding of GIA and ice
mass change in Antarctica. We explore ice loading scenarios for the
Wilkes Subglacial Basin (LGM time scale) and the Siple Coast (centennial
and millennial time scales), using GIA models with 1D earth models. We
find that the spatial extent of deformation resulting from Wilkes and
Siple loading is significant, but that no 1D model, regardless of the
earth model and ice loading scenario used, is able to reproduce all
three distinct patterns of observed motion at the same time. For select
loading scenarios, we also examine 3D GIA models by invoking a boundary
in Earth properties beneath the Transantarctic Mountains. This approach
accounts for the strong lateral gradient in earth properties across the
continent by effectively separating East and West Antarctica into two
different earth model profiles. Some of our GIA models utilizing 3D
earth structure are able to reproduce predicted motions that
directionally match all three observed patterns of deformation. Best
fitting ice history and earth models are presented, including preferred
upper mantle viscosity values.