On Sunday, May 18, 1980, news about an eruption of Mount St. Helens, Washington, electrified the world as a mighty landslide and blast stripped 1,300 feet from the mountain's summit, unleashed a mighty eruption of ash and gas that reached an altitude of 80,000 feet in 15 minutes, and opened the volcano to its core.
The blast rushed across valleys and ridges alike at speeds of more than 300 miles-per-hour and destroyed more than 230 square miles of forest and meadowlands as far as 17 miles northwest of the volcano. As ash rose into the atmosphere, prevailing winds blew 520 million tons of ash eastward across the United States, and causing complete darkness in Spokane, Washington, 250 miles away. Hot rocks and gas quickly melted the snow and ice capping the volcano, creating surges of water that eroded and mixed with loose rock to form lahars (volcanic mudflows). The largest lahar destroyed bridges and homes along the Toutle River and eventually flowed about 50 miles into the Cowlitz River causing flooding in Kelso and Longview, Washington. The Cowlitz carried sediment into the Columbia River, where it collected and reduced the depth of the shipping channel from 40 to 14 feet, stranding 31 ships in upstream ports.
Tragically, fifty-seven people lost their lives during this eruption. Countless wildlife and fish populations perished. Downwind of the volcano, in areas of thick ash accumulation, many crops—wheat, apples, potatoes, and alfalfa, were ruined. Mount St. Helens' landscape appeared gray and lifeless, like parts of Earth's moon.
Beginning in October, 1980 and for six years thereafter, small explosions hurled volcanic ash a few hundred feet to several miles above the volcano. During 17 distinct episodes, rebuilding of the mountain commenced as fresh lava oozed from the crater floor and accumulated into a muffin-shaped lava dome. Plants and animals repopulated portions of the barren plains around Mount St. Helens. Avalanches of snow and rock fell from the 2,000 foot high crater walls, and in the shadows transformed into the Northwest's first new glacier in many years. Mount St. Helens was on the mend.
In September 2004, swarms of earthquakes heralded the next awakening of the volcano. Mount St. Helens thrilled observers initially with several spectacular eruptions of volcanic ash and gas before settling into a mostly silent 39-month-long continuous extrusion of lava that built a second lava dome even larger than the first. To date, about 6-percent of the crater has been refilled. During 2008, two branches of Crater Glacier that had been split by the new lava dome, rejoined as one, and now flow from the crater breach.
Over the past 32 years, Mount St. Helens has given the world a legacy with far reaching effects. USGS and visiting scientists have studied the volcano intensively. Many of these scientists have transferred their expertise to other regions of North America and abroad, saving property and thousands of lives. They have learned the importance of keeping track of a volcano's condition by installing sensitive instruments that can record and alert us of new awakenings. Geologists have revealed the eruptive histories of surrounding Cascade volcanoes, and after recognizing risks to many communities, have worked tirelessly with public officials to ensure greater preparedness. All of us who in some way witnessed the events of May 18, 1980 share a collective memory of that unforgettable day, and a responsibility to remind future generations of how volcanic eruptions can cause serious disruptions to our everyday lives. Becoming knowledgeable about the hazards within our communities and then preparing with an emergency plan for our families can help us live in greater safety and comfort now, and with less disruption and faster recovery from the next eruption of a Cascade Range volcano.