Mount St Helens is a volcano in which US state?
1980 eruption of Mount St. Helens Helens has been documented as a continuous eruption with a gradual extrusion of magma at the Mount St. Helens volcano. Starting in October 2004, there was a gradual building of a new lava dome. The new dome did not rise above the caldera created by the 1980 eruption. This activity lasted until January 2008. 1980 eruption of Mount St. Helens On May 18, 1980, a major volcanic eruption occurred at Mount St. Helens, a volcano located in Skamania County, in the U.S. state of Washington. The eruption (a VEI 5 event) was the most significant volcanic eruption to occur in
Mount St. Helens 1980 eruption. Mount St. Helens is west of Mount Adams, in the western part of the Cascade Range. These "sister and brother" volcanic mountains are approximately from Mount Rainier, the highest of Cascade volcanoes. Mount Hood, the nearest major volcanic peak in Oregon, is southeast of Mount St. Helens. Mount St. Helens is geologically young compared with the other major Cascade volcanoes. It formed only within the past 40,000 years, and the pre-1980 summit cone began rising about 2,200 years ago. The volcano is considered the most active in the Cascades within the Holocene epoch (the last 10,000 or so