The 1980 eruption of Mount St. Helens was one of the most closely studied volcanic eruptions in the arc and one of the best studied ever . It was a Plinian style eruption with a VEI = 5 and was the most significant to occur in the lower 48 U.S. states in recorded history . An earthquake at 8:32 a.m. on May 18 , 1980 , caused the entire weakened north face to slide away . An ash column rose high into the atmosphere and deposited ash in 11 U.S. states . The eruption killed 57 people and thousands of animals and caused more than a billion U.S. dollars in damage
1980 eruption of Mount St. Helens
1980 eruption of Mount St. Helens
Cascade Volcanoes