In the spring of 1980, a series of earthquakes and small eruptions drew the attention of people living in the Pacific Northwest. Scientists and sightseers were drawn to Mount St. Helens. Steam vents, tremors and hot spots appeared almost daily.
Then on May 18, a 5.1-magitude earthquake shook the mountain. For a few seconds the north flank seemed to ripple, then broke loose and began sliding downhill as a massive avalanche. Eruption plumes shot up as quickly as 600 miles an hour. The blast traveled as a hot, churning mass of gas, rock, ash and ice. More than 50 people were killed or reported missing after the blast, and the eruption devastated 235 square miles. read more