Chile's Chaiten volcano one of scores of active volcanoes in region, says CU-Boulder professor

Aerial view Chaiten Volcano, southern Chile, prior to May 2008 eruption. Click here for more information.

The Chaiten volcano now erupting in southern Chile is one of 200 to 300 volcanoes in the "Andean Arc" region of Chile, Peru, Ecuador and Columbia considered active by volcanologists, some of which lie in much more densely populated areas, said a University of Colorado at Boulder geologist who has studied Chaiten.

While the public perception is that volcanoes that have not erupted in historic times are dormant, volcanologists consider any volcanoes that erupted during the last 10,000 years during the Holocene Period -- including Chaiten -- to be potentially active, said CU-Boulder geological sciences department Professor Charles Stern.

Stern said the pyroclastic flow and ash-fall deposits he and Chilean colleagues analyzed in 2004 indicate Chaiten last erupted about 9,370 years ago. "We consider the lifespan of Andean volcanoes to be about 1 million years, which is supported by this new eruption," he said.

He said Chaiten, which started to erupt on Friday and which "ramped up significantly" today, could bury the nearby town of Chaiten much like the Roman city of Pompeii was buried by tephra, or volcanic material, following the eruption of Mount Vesuvius in 79 A.D.

"There are 25 million to 30 million people that live very close to at least one of these potentially active volcanoes in the Andean Arc, including the cities of Quito and Santiago," said Stern. "This is a good example of what could happen at any time in the region, and it is fortunate the Chaiten eruption is occurring in a pretty sparsely populated area."