YELLOWSTONE NATIONAL PARK, Wyo. - The Yellowstone caldera has been classified a high threat for volcanic eruption, according to a report from the U.S. Geological Survey.Yellowstone ranks 21st most dangerous of the 169 volcano centers in the United States, according to the Geological Survey's first-ever comprehensive review of the nation's volcanoes.Kilauea in Hawaii received the highest overall threat score followed by Mount St. Helens and Mount Rainier in Washington, Mount Hood in Oregon and Mount Shasta in California. Kilauea has been erupting since 1983. Mount St. Helens, which erupted catastrophically in 1980, began venting again in 2004.Those volcanoes fall within the very high threat group, which includes 18 systems. Yellowstone is classified with 36 others as high threat.Recurring earthquake swarms, swelling and falling ground, and changes in hydrothermal features are cited in the report as evidence of unrest at
