volcanic eruption

Last year, rare footage of a documentary on Mount St. Helens volcanic eruption from the late 1980s was shared on YouTube. https://www.youtube.com/watch?v=3zHgwiOK3oU The documentary shows old photographs from before the eruption dating back to the 1950s, exploring the campgrounds, parks, lakes, and forested areas, now changed forever by the destructive forces of the volcano erupting in 1980. Mount St. Helens formed 275,000 years ago. March 27, 1980, the volcano erupted, closing the Gifford Pinchot National Park, and bringing thousand of scientists and forest service experts to the mountain to document every moment of this monumental event. May 18, 1980, the volcano exploded at 8:32am, killing 57 people, and destroying 250 homes, 47 bridges, 15 miles of railroad, and 185 miles of highway. For over nine hours, the plume of ash rose approximately 16 miles above sea level, moving eastward at about 60 miles per hour, reaching Idaho by noon, and Edmonton, Alberta, Canada, by the next day. A debris avalanche triggered by the explosion and earthquake measuring 5.1 on the Richter scale, releasing 24 megatons of thermal energy. It reduced the mountains summit from 9,677 to 8,365 feet, leaving a one mile wide horseshoe-shaped crater, becoming one of the most deadliest and economically destructive volcanic events in the history of the United States. Mt. St. Helens eruption was classified as a VEI 5 event, the only significant such event to happen in the contiguous 48 United States since the 1915 eruption of Lassen Peak in California. Before 1980, the last eruption of St. Helens was 130 years ago.