| Mount St. Helens | |
|---|---|
 3,000 ft (0.9 km) high steam plume on May 19, 1982, two years after the 1980 major eruption | |
| Highest point | |
| Elevation | 8,363 ft (2,549 m) |
| Prominence | 4,605 ft (1,404 m) |
| Listing | |
| Coordinates | 46°11′28″N 122°11′40″W / 46.1912000°N 122.1944000°W[1] |
| Naming | |
| Etymology | Alleyne FitzHerbert, 1st Baron St Helens |
| Native name | |
| Geography | |
  Mount St. Helens Location in Washington state | |
| Parent range | Cascade Range |
| Topo map | USGS Mount St. Helens |
| Geology | |
| Rock age | Less than 40,000 years old |
| Mountain type | Active stratovolcano (Subduction zone) |
| Volcanic arc | Cascade Volcanic Arc |
| Last eruption | 2004–2008 |
| Climbing | |
| First ascent | 1853 by Thomas J. Dryer |
| Easiest route | Hike via south slope of volcano (closest area near eruption site) |
Mount St. Helens (known as Lawetlat'la to the indigenous Cowlitz people, and Loowit or Louwala-Clough to the Klickitat) is an active stratovolcano located in Skamania County, Washington,[1] in the Pacific Northwest region of the United States. It lies 52 miles (83 km) northeast of Portland, Oregon,[2] and 98 miles (158 km) south of Seattle.[3] Mount St. Helens takes its English name from that of the British diplomat Alleyne Fitzherbert, 1st Baron St Helens, a friend of explorer George Vancouver who surveyed the area in the late 18th century.[1] The volcano is part of the Cascade Volcanic Arc, a segment of the Pacific Ring of Fire.
The Mount St. Helens major eruption of May 18, 1980, remains the deadliest and most economically destructive volcanic event in U.S. history.[4] Fifty-seven people were killed; 200 homes, 47 bridges, 15 miles (24 km) of railways, and 185 miles (298 km) of highway were destroyed.[5] A massive debris avalanche, triggered by a magnitude 5.1 earthquake, caused a lateral eruption[6] that reduced the elevation of the mountain's summit from 9,677 to 8,363 ft (2,950 to 2,549 m), leaving a 1 mile (1.6 km) wide horseshoe-shaped crater.[7] The debris avalanche was 0.6 cubic miles (2.5 km3) in volume.[8] The 1980 eruption disrupted terrestrial ecosystems near the volcano. By contrast, aquatic ecosystems in the area greatly benefited from the amounts of ash, allowing life to multiply rapidly. Six years after the eruption, most lakes in the area had returned to their normal state.[9]
After its 1980 eruption, the volcano experienced continuous volcanic activity until 2008. Geologists predict that future eruptions will be more destructive, as the configuration of the lava domes requires more pressure to erupt.[10] However, Mount St. Helens is a popular hiking spot and it is climbed year-round. In 1982, the Mount St. Helens National Volcanic Monument was established by President Ronald Reagan and the U.S. Congress.
- ^ a b c "Mount Saint Helens". Geographic Names Information System. United States Geological Survey, United States Department of the Interior.
- ^ "Distance between Portland and Mount Saint Helens". distancefromto.net. Retrieved 27 March 2021.
- ^ "Distance between Seattle and Mount Saint Helens". distancefromto.net. Retrieved 27 March 2021.
- ^ "Mount St. Helens National Volcanic Monument". USDA Forest Service. Archived from the original on 23 November 2006.
- ^ Tilling, Robert I; Topinka, Lyn; Swanson, Donald A (1990). "Impact and Aftermath". Eruptions of Mount St. Helens: Past, Present, and Future. 1.01. USGS.
- ^ Cite error: The named reference
USGSFrom1980was invoked but never defined (see the help page). - ^ "May 18, 1980 eruption of Mount St. Helens". USDA Forest Service. Archived from the original on 29 May 2009.
- ^ "1980 Cataclysmic Eruption". Mount St. Helens. USGS. Retrieved 27 March 2021.
- ^ "Mount St. Helens: A Living Laboratory for Ecological Research | Pacific Northwest Research Station | PNW - US Forest Service". www.fs.usda.gov. Retrieved 1 June 2021.
- ^ Haas, Maya (18 May 2020). "Mount St. Helens isn't where it should be. Scientists may finally know why". National Geographic. Archived from the original on 3 June 2021. Retrieved 20 June 2021.