If scientists armed with today's monitoring tools and knowledge could step back in time to the two months before May 18, 1980, they would have been able to better forecast the forthcoming devastating eruption.
Mount St. Helens’ 1980 Eruption
Changed the Future of Volcanology
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. 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.
Before 1980, scientists saw sharp divisions among volcano hazard studies, volcano monitoring and basic volcanology research. The 1980 eruption, however, required scientists to work together in a more integrated manner. Mount St. Helens changed the way that scientists do business by linking specialists from many disciplines. Now, 40 years later, it is routine for geologists, seismologists, geophysicists, hydrologists, geochemists and biologists to cooperate in studies of natural science processes resulting in well-integrated research, monitoring and communication.
The eruption also led to a new era of volcanic monitoring. During studies at Mount St. Helens, scientists refined their interpretations of monitoring data in order to better forecast future eruptions. Earthquakes, ground deformation and gas measurements took on new meaning as the volcano demonstrated that patterns of change could help scientists forecast lava-dome building eruptions. Scientists now use similar patterns of change to forecast future activity at volcanoes around the world.
Since the eruption of Mount St. Helens, volcano monitoring has evolved from placing a few scientific instruments on a volcano’s flanks to a broader integrated network of monitoring devices that measure earthquakes, deformation and volcanic gases, and can detect eruptions or changes on the Earth’s surface from space. The evolution of tools like photogrammetry, Geographic Information Systems (GIS), and Light Detection and Ranging (lidar) enable scientists to make precise measurements and illustrations of changes to Earth’s surface, including inflation and deflation at volcanoes. Technological revolutions in telemetry, broad-band seismometer technology, and low-power instrumentation are fueling a new era of volcano monitoring equipment capable of collecting and transmitting real-time data remotely with increased precision, efficiency, portability and value, and with reduced risk to scientists.
The explosive eruption of May 18, 1980, illustrates the importance of developing new tools for measuring ground deformation at explosive volcanoes. Tiltmeters and surveying instruments were the only instruments available for monitoring the large .9- to 1.2-mile bulge (1.5 by 2 km) in the north face of Mount St. Helens in 1980. Today, scientists can remotely use high-precision Global Positioning System receivers, sophisticated borehole tiltmeters and strainmeters, and other sensors to measure and report even small amounts of deformation at the centimeter scale continuously and in real time. In addition, using a remote sensing technique called InSAR (interferometric synthetic aperture radar), they combine satellite radar images to map ground deformation in remarkable detail over large areas. With the experience gained at Mount St. Helens, new deformation monitoring tools have enabled scientists to reduce risks to lives and property globally.
The Mount St. Helens eruption also gave credibility to U.S. volcanologists who were subsequently invited to participate in the response to volcanic crises in other countries. Scientists at the U.S. Geological Survey (USGS) Cascades Volcano Observatory, for example, developed a mobile observatory to help respond to quickly developing volcanic situations. This rapid-deployment capability led to the formation of the Volcano Disaster Assistance Program, which is co-funded by the U.S. Agency for International Development (USAID) and the USGS. VDAP scientists have traveled to volcanoes world-wide to share their experience at Mount St. Helens and to learn from other volcanic events. Since 1986, VDAP has responded to more than two dozen major volcanic crises in a dozen countries.
Now, let’s step into to the future. The eruption of Mount St. Helens has influenced volcanology in many ways, and the next step in this evolution is the National Volcano Early Warning System, or NVEWS. In March 2019, USGS was authorized by Congress to develop and implement NVEWS to more fully monitor volcanoes and to warn and protect citizens of the United States from danger caused by volcanic activity. When NVEWS is fully implemented, all hazardous U.S. volcanoes will be monitored at levels consistent with the threat they pose to communities, infrastructure and aviation. Pro-active early warning of a potential eruption is key to minimizing loss of life and economic disruption by increasing the time that emergency managers can initiate mitigation measures, improve evacuation alerts and better position resources for recovery. Earliest detection of eruption precursors with multiple instrument types allows for more accurate forecasts of hazardous eruptive activity needed by land managers and the aviation sector.
As we reflect on the influences of the Mount St. Helens eruption over the last 40 years, we should remember that many volcanoes are basically unstable mountains. They grow by piling up lava and ash into cones with steep-sided slopes that are prone to collapse causing massive landslides known as debris avalanches. The debris avalanche caused by the 1980 eruption was the third large debris avalanche known to have happened there in the last 20,000 years. By understanding its history, scientists know that over time Mount St. Helens will be rebuilt again, a process already evident in the volcano’s 2004 eruptive events.
To learn more about how the eruption influenced Volcanology please read, “Ten Ways Mount St. Helens Changed Our World—The Enduring Legacy of the 1980 Eruption.”