Mount St. Helens May 18, 1980 eruption
Credit: USGS Photograph taken on May 18, 1980, by Austin Post
On May 18, 1980, at 8:32 a.m. Pacific Daylight Time, a magnitude 5.1 earthquake shook Mount St. Helens. The bulge and surrounding area slid away in a gigantic rockslide and debris avalanche, releasing pressure, and triggering a major pumice and ash eruption of the volcano.
