The 1980 Mount St. Helens eruption began with a steady series of earthquakes in March. By April it began spewing smoke, massive landslides on the north side of the mountain began, as a massive bulge a half-mile wide crept six feet a day up the mountainside.

Mount St. Helens, the largest volcanic eruption in US history, was commemorated this weekend, 45 years after its eruption, which killed 57 people and spewed ash across 11 US states and 5 Canadian provinces,

Mount St. Helens erupted, killing dozens and forever changing how the US monitors earthquakes. The volcano is still active but not erupting.