Thursday, October 11, 2012
A slow upward push of magma over the last two decades has caused a 62-mile-wide formation in the earth's crust in South America that's roughly in the shape of a sombrero, researchers at the Scripps Institution of Oceanography said today.
The uplift is located in the Andes Mountain Range near where Argentina, Bolivia and Chile come together. While the huge area rises, the surrounding crust sinks, creating the sombrero effect.
Scientists led by Yuri Fialko of Scripps and Jill Pearse of the Alberta Geological Survey made the discovery while pouring over 20 years of satellite data. They said the earth's surface is rising about as fast as a fingernail grows.
"It's a subtle motion, pushing up little by little every day, but it's this persistence that makes this uplift unusual,'' said Fialko, a professor of geophysics in the Cecil H. and Ida M. Green Institute of Geophysics and Planetary Physics at Scripps. "Most other magmatic systems that we know about show episodes of inflation and deflation.''
He said a similar blob of magma is pushing up at the earth's crust in New Mexico, but at a much lower rate.
"Satellite data and computer models allowed us to make the important link between what's observed at the surface and what's happening with the magma body at depth,'' Fialko said.
The sombrero uplift could help scientists understand the initial stages of "super volcano'' events thousands of times stronger than last year's eruption in Iceland, he said.