VolcanoesMount St. Helens’ 1980 Eruption Changed Volcanology

Published 18 May 2020

If scientists armed with today’s monitoring tools and knowledge could step back in time to the two months before 18 May 1980, they would have been able to better forecast the forthcoming devastating eruption.

If scientists armed with today’s monitoring tools and knowledge could step back in time to the two months before 18 May 1980, they would have been able to better forecast the forthcoming devastating eruption.

Forty years ago, after two months of earthquakes and small explosions, Mount St. Helens cataclysmically erupted. A high-speed blast leveled millions of trees and ripped soil from bedrock. The eruption fed a towering plume of ash for more than nine hours, and winds carried the ash hundreds of miles away. Lahars (volcanic mudflows) carried large boulders and logs, which destroyed forests, bridges, roads and buildings. These catastrophic events led to 57 deaths, including that of David Johnston, a dedicated USGS scientist, and caused the worst volcanic disaster in the recorded history of the conterminous United States. 

Had we known then what we know today about volcanoes, could the loss of life and economic damage caused by the Mount St. Helens eruption have been prevented or mitigated?

For the answer, let’s travel forward to the present. USGS says that over the past 40 years, technology and the scientific study of volcanoes have made significant advances.  Better cooperation, monitoring and forecasting possibly could have allowed for earlier evacuations, hazard mitigation and reduced risk. But the truth is the eruption of Mount St. Helens sparked the advances in cutting-edge volcano science and monitoring that exist today. 

Mount St. Helens turned out to be the ideal laboratory to study volcanic activity. The 1980 eruption was the first large explosive eruption studied by scientists and observers using modern volcanology. The volcano was also easily viewed and accessible. As a result, the eruption and its effects were heavily photographed from numerous vantage points. The debris avalanche opened the cone, and scientists were able to inspect its interior in a new and novel way. The eruption jump-started interest in the study of explosive eruptions and monitoring efforts to improve warning systems that help mitigate hazards. The eruption underscored the importance of using as many monitoring tools as possible to track unrest and eruption activity.

The north flank collapse and eruption at Mount St. Helens also informed volcano scientists on how to interpret the hummocky terrain near other Cascades volcanoes, such as California’s Mt. Shasta. We now know that type of terrain is evidence of a past flank collapse at that volcano about between 300,000 and 380,000 years ago that occurred without an eruption.