Mount St Helens Eruption, Exactly What Happened 35 Years Ago (Photos, Video)

The eruption of Mount St. Helens on May 18, 1980 was not a one-day event. It had been building for 2 months, but when it happened, it was without warning.

Ash column from the eruption of Mount St. Helens on May 18, 1980 from the southwest. Mount Adams is in the background. USGS

The violent eruption of Mount St. Helens on May 18, 1980 was not a one day event. For two months magma had been accumulating below the volcano, creating a huge ominous bulge on the mountain’s north slope, and generating thousands of small earthquakes.

A USGS geologist at Coldwater II observation post watching Mount St. Helens. USGS