Inflating volcanoes of South America: Scientists learn what fuels a super eruption

April 4, 2011


High in the Andes Mountains, a few volcanoes have been inflating for decades despite not having erupted in hundreds of thousands of years. Geophysical Institute scientists lead a South American-based project to study the world’s largest body of magma and its implications in a land of super eruptions.


Over the next five years, Research Professor Steve McNutt, Assistant Research Professor Mike West, and Professor Doug Christensen will help deploy seismometers and GPS equipment on the volcanic flanks of the 6,008-meter Uturuncu in Bolivia, and a region called Lazufre that is composed of two mountains in a complex of high volcanoes on the border between Chile and Argentina on the project.


The GI professors have partnered with Matt Pritchard of Cornell University, researchers from Montana State University, the University of California Santa Cruz, Oregon State University, the University of Alberta and colleagues from Bolivia, Chile and Argentina.


Geologists were more interested in other Andes volcanoes until Pritchard looked at a wide swath of the world’s longest mountain range with interferometric synthetic aperture radar (InSAR). Using the technology that allows researchers to see subtle changes in surface elevation, Pritchard noticed that four volcanoes were deforming at a rapid rate. The most active, Uturuncu, had been inflating one to two centimeters per year since the InSAR technique was first developed in the 1990s. Scientists contend a massive pool of magma located about 17-20 kilometers beneath the surface is responsible for the volcanoes’ swelling.


Pritchard shared his discovery with McNutt in 2003. Once in the region, McNutt carried a portable seismometer to the specific area in the Andes and recorded 29 earthquakes in the first two hours.


“Twenty-seven of those were similar, which tells us they were all coming from the same spot,” McNutt said. “We were right on the flank of (Uturuncu), close to the deformation center.”


This special section of the Andes will also teach volcanologists about conditions that give birth to super eruptions, which, lucky for humanity, only occur about once every 10,000 years. 


“They are kinds of eruptions that when they happen, ‘massive’ doesn’t really describe it,” West said. “They are larger than what we’ve seen in recorded history. The sort of comparison most people make is about 100 times the volume of Mount St. Helens.”