Researchers ID Unique Geological ’Sombrero’ Uplift in South America

World's largest magma system forcing protrusion in the Andes, possibly providing clues into the birth of 'super volcanoes'. Scientists at Scripps Institution of Oceanography at UC San Diego have used 20 years of satellite data to reveal a geological oddity unlike any seen on Earth. At the border of Argentina, Bolivia and Chile sits the Altiplano-Puna plateau in the central Andes region, home to the largest active magma body in Earth's continental crust and known for a long history of massive volcanic eruptions. A study led by Yuri Fialko of Scripps and Jill Pearse of the Alberta Geological Survey has revealed that magma is forming a big blob in the middle of the crust, pushing up the earth's surface across an area 100 kilometers (62 miles) wide, while the surrounding area sinks, leading to a unique geological phenomenon in the shape of a Mexican hat that the researchers have described as the "sombrero uplift." Since the magma motion is happening at a great depth and at a fairly slow rate-the earth's surface rises at about a centimeter per year or roughly the rate fingernails grow-there is no immediate danger of a volcanic outpouring, the researchers said. The details of "It's a subtle motion, pushing up little by little every day, but it's this persistence that makes this uplift unusual. Most other magmatic systems that we know about show episodes of inflation and deflation," said Fialko, a professor of geophysics in the Cecil H. and Ida M. Green Institute of Geophysics and Planetary Physics at Scripps.