Mount St. Helens

Mount St. Helens is an active stratovolcano in Skamania County, Washington, in the Cascade Range of the Pacific Northwest, about 52 miles northeast of Portland, Oregon, and currently 8,363 feet high after losing roughly 1,300 feet of elevation in its 1980 eruption. On May 18, 1980, a magnitude 5.1 earthquake triggered the largest debris avalanche in recorded history as the volcano's north face collapsed, followed by a lateral blast and eruption that killed 57 people, destroyed more than 200 homes and 185 miles of highway, and released energy equivalent to 24 megatons of TNT. The volcano remained intermittently active through 2008 and is rated a very high threat by the United States Geological Survey, which monitors it closely through the Cascades Volcano Observatory, though it has since reopened to climbers and hikers.