18 Most Dangerous U.S. Volcanoes Include Erupting Alaska Peak

Spewing ash and steam miles into the sky, Alaska’s Augustine Island volcano has been erupting this week and posing a threat to air traffic.

The newly vigorous mountain is just one of the 18 most dangerous U.S. volcanoes, according to a report presented by John Ewert at a meeting of the American Geophysical Union in San Francisco last month. Ewert is a Vancouver, Washington-based volcanologist with the U.S. Geological Survey.