Mount St. Helens

Mount St. Helens, one day before the devastating eruption

Cascade Range plate tectonics-en

East Dome Mount St. Helens

1890 Clohessy and Strengele engraving of Mount St Helens (cropped)

MSH-10B Mount St. Helens Erupts, Portland View, May 18, 1980 (22636191326)

Mount St. Helens is an active stratovolcano located in Skamania County, Washington, in the Pacific Northwest region of the United States. It is part of the Cascade Range of volcanoes and became famous for its catastrophic eruption on May 18, 1980. This event was the deadliest and most economically destructive volcanic eruption in the history of the United States. The eruption reduced the elevation of the mountain's summit from 9,677 feet (2,950 meters) to 8,363 feet (2,549 meters), leaving a 1 mile (1.6 km) wide horseshoe-shaped crater. The area surrounding the volcano is part of the Mount St. Helens National Volcanic Monument, a protected area for research, recreation, and education.

Geology

Mount St. Helens is known for its explosive and dome-building eruptions. The mountain's geology is a result of its location at the convergent plate boundary where the Juan de Fuca Plate is subducting beneath the North American Plate. This process is responsible for the volcanic activity in the Cascade Volcanic Arc, including Mount St. Helens. Prior to the 1980 eruption, the volcano had a history of periodic eruptions dating back thousands of years, with the most recent significant activity occurring in 1857.

1980 Eruption

The 1980 eruption of Mount St. Helens was preceded by a series of earthquakes and steam-venting episodes, indicating that magma was moving below the surface. On the morning of May 18, a magnitude 5.1 earthquake triggered a massive lateral blast, which blew off the north face of the mountain. This was followed by a plinian eruption that sent ash and volcanic gases into the atmosphere, which then fell over large areas of the western United States. The eruption caused significant loss of life, property damage, and altered the landscape around the mountain. Fifty-seven people were killed, and hundreds of square miles were reduced to wasteland, causing over a billion dollars in damages.

Ecological Recovery

Following the eruption, the area around Mount St. Helens became a natural laboratory for studying ecological recovery. The Mount St. Helens National Volcanic Monument was established to preserve the volcano and allow for its aftermath to be scientifically studied. The region has since been a site for research on succession, the process by which ecosystems recover and develop after a disturbance. Studies have shown how plant and animal life have recolonized the blast zone, providing valuable insights into ecological resilience and adaptation.

Recreation

Mount St. Helens is a popular destination for outdoor activities, including hiking, camping, and mountain climbing. The Johnston Ridge Observatory and the Ape Caves offer visitors educational experiences and spectacular views of the volcano and its surrounding landscape. Climbing permits are required for those wishing to summit the volcano, emphasizing the need to balance recreation with preservation and safety.

See Also

• 1980 eruption of Mount St. Helens
• Cascade Volcanoes
• Volcanic ash
• Lahar