Mount St. Helens Reloaded

On May 18, 1980, Mount St. Helens, Washington, exploded in a spectacular and devastating eruption that shocked the world. The eruption, one of the most powerful in the history of the United States, lowered the mountain’s summit elevation from 2,950 meters to 2,549 meters, leaving a north-facing, horseshoe-shaped crater more than two kilometers wide. Most of the forest surrounding the volcano was destroyed and 57 people were killed. After the 1980 eruption, Mount St. Helens remained active. A large lava dome episodically extruded in the center of the volcano’s empty crater until 1986. During the two decades following the May 18, 1980, eruption, a new glacier, Crater Glacier, formed tongues of ice around the east and west sides of the lava dome in the deeply shaded niche between the lava dome and the south crater wall.

As the most active volcano in the Cascade Range with a complex 300,000-year history, Mount St. Helens erupted again in the fall of 2004 as a new period of dome building within the 1980 crater began. Lava erupted just south of the 1980–1986 lava dome, cracking and bulldozing Crater Glacier. The volume of the new lava dome, during less than two years of eruption, is roughly equal to that of the 1980–1986 lava dome, and it continues to grow.

GIS technology is an important part of the response to this ongoing eruption. GIS is being used to estimate extruded growth rates and volumes of the new lava dome; to catalog remote instruments used to monitor the volcano; to forecast the potential directions, extents, and ashfall amounts associated with volcanic ash plumes; and to analyze and visualize volcanic hazards associated with the eruption. These efforts are important in understanding the mechanics of the eruption; planning effective instrument deployment; and informing federal, state, and local officials of potential dangers posed by continuing volcanic activity.

Courtesy of U.S. Geological Survey.