Watch Fire Mountain: The Eruption and Rebirth of Mount St. Helens for Free: How to Stream the Movie Online at 123Movies. . In 1980, the eruption of Mount St. Helens leveled 230 square miles, sent 540 million tons of ash and volcanic rock twelve miles into the air, and blasted one cubic mile of earth from the crest of the Cascade Mountain Range. Illustrates the terrifying fury of the most destructive volcanic disaster in American history through aerial photography and survivors' own words. Shows examples of nature's plant and animal recovery seventeen years later.