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Antarctica has apparently been living by the lyrics of Carole King’s 1971 hit song “The Earth Moves Under My Feet”. According to a study from Newcastle University in the United Kingdom, Antarctica has been moving “rapidly”. Recently published in Earth and Planetary Science Letters, the study explains why the upward motion of the Earth’s crust in the Northern Antarctic Peninsula is currently taking place so quickly. While earlier studies have shown the earth is ‘rebounding’ due to the overlying ice sheet shrinking in response to climate change, GPS data is suggesting otherwise. The international research team led in part by Newcastle researchers has revealed that this land is rising at a remarkable rate of 15mm a year.
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This movement of the land was understood to be
due to an instantaneous, elastic response followed by a very slow uplift over
thousands of years. But the new data demonstrates a much higher rise than can
be accounted for by the present-day elastic response alone.
They now know the mantle below the Earth’s crust
in the Antarctic Peninsula is flowing much faster, presumably due to subtle
changes in temperature or chemical composition making it flow more easily
responding more quickly to the lightening load hundreds of miles above it, thereby
changing the land’s shape.
Lead researcher, PhD student Grace Nield,
explains: “You would expect this rebound to happen over thousands of years and
instead we have been able to measure it in just over a decade. You can
almost see it happening which is just incredible. Because the mantle is ‘runnier’ below the
Northern Antarctic Peninsula it responds much more quickly to what’s happening
on the surface. So as the glaciers thin and the load in that localized
area reduces, the mantle pushes up the crust.
“At the moment we have only studied the vertical
deformation so the next step is to look at horizontal motion caused by the ice
unloading to get more of a 3-D picture of how the Earth is deforming, and to
use other geophysical data to understand the mechanism of the flow.”
Since 1995 several ice shelves in the Northern
Antarctic Peninsula have collapsed and triggered ice-mass unloading, causing
the solid Earth to ‘bounce back’.
“Think of it a bit like a stretched piece of
elastic,” says Nield. “The ice is pressing down on the Earth and as this
weight reduces the crust bounces back. But what we found when we compared
the ice loss to the uplift was that they didn’t tally — something else had to
be happening to be pushing the solid Earth up at such a phenomenal rate.”
Read more from Newcastle
University.
Ice
Flows image via Shutterstock.
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