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, in the Pacific Northwest region of the United States. It lies northeast of Portland, Oregon, and south of Seattle. Mount St. Helens takes its English name from that of the British diplomat Lord St Helens, a friend of explorer George Vancouver who surveyed the area in the late 18th century. 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. Fifty-seven people were killed; 200 homes, 47 bridges, of railways, and of highway were destroyed. A massive debris avalanche, triggered by a magnitude 5.1 earthquake, caused a lateral eruption that reduced the elevation of the mountain's summit from to , leaving a wide horseshoe-shaped crater. The debris avalanche was in volume. 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. 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. 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. Geographic setting and description General Mount St. Helens is west of Mount Adams, in the western part of the Cascade Range. Considered "brother and sister" mountains, the two volcanoes are approximately from Mount Rainier, the highest of the Cascade volcanoes. Mount Hood, the nearest major volcanic peak in Oregon, is southeast of Mount St. Helens. Mount St. Helens is geologically young compared with the other major Cascade volcanoes. It formed only within the past 40,000 years, and the summit cone present before its 1980 eruption began rising about 2,200 years ago. The volcano is considered the most active in the Cascades within the Holocene epoch, which encompasses roughly the last 10,000 years. Prior to the 1980 eruption, Mount St. Helens was the fifth-highest