Mount St. Helens, located in southwestern Washington State, erupted on May 18, 1980 at 8:32 a.m. Pacific Daylight Time. Before the eruption, the elevation of the volcano had been 9,677 feet. Afterward, it was 8,363 feet, having lost 1,314 feet in elevation. The explosion blew out the northwest side of the mountain and pulverized about a third of the volcano, which turned into mud and ash. The ash cloud blackened the sky as it traveled eastward, leaving detectable amounts of ash over an area of 22,000 square miles. The ash cloud reached a height of about 80,000 feet in less than 15 minutes after the eruption. It spread across the U.S. in 3 days and circled the globe in 15 days. In all, 1.4 billion cubic yards of ash were thrown into the air by the eruption of Mount St. Helens.
This guide provides links to a selection of archival, print, and photographic materials relating to the 1980 eruption of Mount St. Helens.
Mount St. Helens eruption cloud seen from 55th Ave. N.E., Seattle, July 22, 1980