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Geophysics Seminar - Jacky Austermann "Imaging Mantle Viscosity and Why it Matters for Ice Age Climate", Columbia

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Jacky Austermann is an Assistant Professor at Columbia University and part of the Seismology, Geology and Tectonophysics Division of Lamont-Doherty Earth Observatory. In her research, she studies sea level changes ranging from the past glacial cycles to Millions of years ago in order to infer ice mass changes and ice sheet stability as well as constrain the Earth's rheology. She also works on geodynamic and plate tectonic problems dealing with plate driving forces and dynamics of the Earth's deep interior.

Abstract

I will present work that aims to constrain Earth’s viscosity based on sea level records and the glacial isostatic adjustment (GIA) process. I will show a local inference for the western US followed by laying out a framework that allows imaging global 3D varying viscosity in Earth’s interior. This framework draws on approaches from seismic tomography and I will present first tests with synthetic data that shows the potential for this technique. In the second part of the talk I will explore how GIA feeds back into affecting the Laurentide ice sheet. We include proglacial lakes (lakes that form at the ice sheet margin) in our GIA model and show that they can speed glacial collapse. Since GIA causes proglacial lakes to be bigger during the deglaciation than the glaciation, this process contributes to the sawtooth shape of ice age climate.

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