The mantle below the earth’s crust in Antarctica is flowing much faster than expected owing to ice melting at a greater speed on the surface, research has shown.
“Seeing this sort of deformation of the earth at such a rate is unprecedented in Antarctica. What is particularly interesting here is that we can actually see the impact that glacier thinning is having on the rocks 400 km down,” explained Peter Clarke, a professor of geophysical geodesy at Newcastle University.
At the surface, Antarctica appears to be a motionless and frozen landscape.
The new study explains for the first time why the upward motion of the earth’s crust in the Northern Antarctic Peninsula is currently taking place so quickly.
The GPS data collected by an international research team has revealed that the land in this region is actually rising at a phenomenal rate of 15mm a year – much greater than can be accounted for by the present-day elastic response alone.
This means it can flow more easily and so responds much more quickly to the lightening load hundreds of miles above it, changing the shape of the land.
“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,” informed lead researcher Grace Nield from Newcastle University.
“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 3D picture of how the earth is deforming,” Nield added.
Since 1995, several ice shelves in the Northern Antarctic Peninsula have collapsed and triggered ice-mass unloading, causing the solid earth to ‘bounce back’.
Because the mantle is ‘runnier’ below the Northern Antarctic Peninsula, it responds much more quickly to what is happening on the surface.
So as the glaciers thin and the load in that localised area reduces, the mantle pushes up the crust, said the research published in the journal Earth and Planetary Science Letters.
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