Quick facts for kidsMount St. Helens
3,000 ft (1 km) steam plume on May 19, 1982, two years after its major eruption
|Elevation||8,365 ft (2,550 m)|
|Prominence||4,605 ft (1,404 m)|
|Location||Skamania County, Washington, U.S.|
|Parent range||Cascade Range|
|Topo map||USGS Mount St. Helens|
|Age of rock||< 40,000 yrs|
|Mountain type||Active stratovolcano|
|Volcanic arc||Cascade Volcanic Arc|
|Last eruption||2004 – July 10, 2008|
|First ascent||1853 by Thomas J. Dryer|
|Easiest route||Hike via south slope of volcano (closest area near eruption site)|
Mount St. Helens is a volcano in the U.S. state of Washington. It is 96 miles (154 km) south of Seattle and 53 miles (85 km) northeast of Portland, Oregon. The volcano is in Cascade Range of mountains. It is part of the Cascade Volcanic Arc in the Pacific Ring of Fire that includes over 160 active volcanos. Mount St. Helens was first called Louwala-Clough, which means "smoking" or "fire mountain" in the language of the Native American Klickitat people.
This volcano is well known for its explosions and flows of lava. Its most famous volcanic eruption was on May 18, 1980. In 1982, U.S. President Ronald Reagan and the United States Congress made the Mount St. Helens National Volcanic Monument, a 110,000 acre (445 km²) area around the volcano that is also a part of the Gifford Pinchot National Forest.
The 1980 eruption was the deadliest and most economically destructive volcanic event in the history of the United States. 57 people were killed; 250 homes, 47 bridges, 15 miles of railways, and 185 miles of highway were destroyed. A massive debris avalanche was triggered by an earthquake measuring 5.1 on the Richter scale. This caused the eruption, which reduced the height of the mountain's summit from 9,677 ft (2,950 m) to 8,365 ft (2,550 m) and replacing it with a 1 mile (1.6 km) wide horseshoe-shaped crater. The earthquake was caused by a sudden surge of magma from the Earth's mantle. The debris avalanche was up to 0.7 cubic miles (3.1 cubic kilometers) in volume.
Before the eruption in 1980, Mount St. Helens was the fifth-highest peak in Washington State. The peak rose more than 5,000 feet (1,525 m) above its base, where it rises from the ridges that are around it. It stood out from the surrounding hills because of the symmetrical cone shape and the snow that covered the top. Because of its cone-shape, it was called the "Mount Fuji of America", after the famous Mount Fuji which is a symbol of Japan.
In the months before the large eruption that took place on May 18, 1980, there were many signs of volcanic activity. On March 20, 1980, Mount St. Helens was the center of a magnitude 4.2 earthquake. Steam venting from the volcano started on March 27. By the end of April, the north side of the volcano started to grow larger.
On May 18, a second earthquake of magnitude 5.1 made a huge part of the north face of the volcano collapse. It was the largest known debris avalanche in recorded history. At 8:32 a.m. Pacific Daylight Time, the magma inside of St. Helens exploded. On the Volcanic Explosivity Index scale, the eruption was rated a five, which is the same rating of the famous Vesuvius eruption in 79 AD.
For more than nine hours, ash erupted from the volcano, rising into the air for 12 to 16 miles (20 to 27 km) above sea level in the air. This cloud rising from a volcano is called a "plume". The pyroclastic flow of heated rocks and gas that poured out of the Volcano spread over an area of over 230 square miles (600 km²), destroying plants and buildings. The ash spread east at about 60 miles per hour (95 km/h), with some ash reaching Idaho by about 12:00 pm, almost 3.5 hours after the eruption. By about 5:30 pm the plume of ash became smaller. Through the night and for several days after, there were smaller eruptions.
As well as the effect of the fast-moving hot gasses and stones from the explosion, the collapse of the northern side of Mount St. Helens caused lahars, or volcanic mudflows. These were mixtures of volcanic ash with melted ice and snow. The lahars went many miles down the Toutle and Cowlitz rivers, destroying bridges and killing many trees. A total of 3.9 million cubic yards (3.0 million m³) of material was carried 17 miles (27 km) south into the Columbia River by the lahars.
The St. Helens May 18 eruption released 24 megatons of thermal energy. It released more than 0.67 cubic miles (2.8 cubic km) of ash and other material. The collapse of the north side of the volcano shortened St. Helens' height by about 1,300 feet (400 m) and left a volcanic crater one to two miles (1.6 to 3.2 km) wide and half of a mile (800 m) deep. The eruption killed 57 people, nearly 7,000 game animals (deer, elk, and bear), and about 12 million fish from a fish farm. It destroyed or damaged over 200 homes, 185 miles (300 km) of highway and 15 miles (24 km) of railways.
Between 1980 and 1986, more volcanic activity continued at Mount Saint Helens, with a new lava dome made in the crater. Several small explosions and eruptions took place, making more lava domes. From December 7, 1989 to January 6, 1990, and from November 5, 1990 to February 14, 1991, the volcano erupted with sometimes huge clouds of ash.
The ash reached a number of states, as far east as Montana and as south as Colorado.
2004 to present activity
Magma bubbles came to the top of the volcano on about October 11, 2004, and a new lava dome was made on the first dome's south side. This new dome grew throughout 2005 and into 2006. Several new features were seen, such as the "whaleback," which is solid magma being pushed to the top of the volcano by magma under it. These features do not last long and break down soon after they are formed. On July 2, 2005, the tip of the whaleback broke off, and a rockfall sent ash several hundred meters into the air.
Mount St. Helens showed important new activity on March 8, 2005, when a 36,000-foot (11,000 m) plume of steam and ash came from the volcano. The plume was seen from as far away as Seattle, a city that is 96 miles away. This fairly small eruption took place because of a new lava dome being formed and a 2.5 magnitude earthquake.
Another feature that grew from the dome is a "fin" or "slab." About half the size of a football field, the large volcanic rock was being moved up as fast as 6 feet (2 m) per day. In mid-June 2006, the slab had rockfalls very often, but was still being pushed up from inside the volcano.
On October 22, 2006, at 3:13 p.m. PST, a magnitude 3.5 earthquake broke the lava dome. The resulting collapse and avalanche sent an ash plume 2,000 feet (610 m) over the crater, although it quickly disappeared.
On December 19, 2006, a large white plume of steam was seen, and some journalists from the media thought there had been a small eruption. However, the Cascades Volcano Observatory of the United States Geological Survey says that there was no large ash plume, so it could not have been an eruption. The volcano has been erupting on occasion since October 2004.
Importance to Indigenous Tribes
Native American lore contains numerous stories to explain the eruptions of Mount St. Helens and other Cascade volcanoes. The most famous of these is the Bridge of the Gods story told by the Klickitat people.
In the story, the chief of all the gods and his two sons, Pahto (also called Klickitat) and Wy'east, traveled down the Columbia River from the Far North in search for a suitable area to settle.
They came upon an area that is now called The Dalles and thought they had never seen a land so beautiful. The sons quarreled over the land, so to solve the dispute their father shot two arrows from his mighty bow – one to the north and the other to the south. Pahto followed the arrow to the north and settled there while Wy'east did the same for the arrow to the south. The chief of the gods then built the Bridge of the Gods, so his family could meet periodically.
When the two sons of the chief of the gods fell in love with a beautiful maiden named Loowit, she could not choose between them. The two young chiefs fought over her, burying villages and forests in the process. The area was devastated and the earth shook so violently that the huge bridge fell into the river, creating the cascades of the Columbia River Gorge.
For punishment, the chief of the gods struck down each of the lovers and transformed them into great mountains where they fell. Wy'east, with his head lifted in pride, became the volcano known today as Mount Hood. Pahto, with his head bent toward his fallen love, was turned into Mount Adams. The beautiful Loowit became Mount St. Helens, known to the Klickitats as Louwala-Clough, which means "smoking or fire mountain" in their language (the Sahaptin call the mountain Loowit).
The mountain is also of sacred importance to the Cowlitz and Yakama tribes that also live in the area. They find the area above its tree line to be of exceptional spiritual significance, and the mountain (which they call "Lawetlat'la", roughly translated as "the smoker") features prominently in their creation story, and in some of their songs and rituals. In recognition of its cultural significance, over 12,000 acres (4,900 ha) of the mountain (roughly bounded by the Loowit Trail) have been listed on the National Register of Historic Places.
Other area tribal names for the mountain include "nšh´ák´" ("water coming out") from the Upper Chehalis, and "aka akn" ("snow mountain"), a Kiksht term.
Exploration by Europeans
Royal Navy Commander George Vancouver and the officers of HMS Discovery made the Europeans' first recorded sighting of Mount St. Helens on 19 May 1792, while surveying the northern Pacific Ocean coast. Vancouver named the mountain for British diplomat Alleyne Fitzherbert, 1st Baron St Helens on 20 October 1792, as it came into view when the Discovery passed into the mouth of the Columbia River.
Years later, explorers, traders, and missionaries heard reports of an erupting volcano in the area. Geologists and historians determined much later that the eruption took place in 1800, marking the beginning of the 57 year-long Goat Rocks Eruptive Period (see geology section). Alarmed by the "dry snow," the Nespelem tribe of northeastern Washington supposedly danced and prayed rather than collecting food and suffered during that winter from starvation.
In late 1805 and early 1806, members of the Lewis and Clark Expedition spotted Mount St. Helens from the Columbia River but did not report either an ongoing eruption or recent evidence of one. They did however report the presence of quicksand and clogged channel conditions at the mouth of the Sandy River near Portland, suggesting an eruption by Mount Hood sometime in the previous decades.
In 1829 Hall J. Kelley led a campaign to rename the Cascade Range as the President's Range and also to rename each major Cascade mountain after a former President of the United States. In his scheme Mount St. Helens was to be renamed Mount Washington.
European colonization and use of the area
The first authenticated non-Indigenous eyewitness report of a volcanic eruption was made in March 1835 by Meredith Gairdner, while working for the Hudson's Bay Company stationed at Fort Vancouver. He sent an account to the Edinburgh New Philosophical Journal, which published his letter in January 1836. James Dwight Dana of Yale University, while sailing with the United States Exploring Expedition, saw the quiescent peak from off the mouth of the Columbia River in 1841. Another member of the expedition later described "cellular basaltic lavas" at the mountain's base.
In late fall or early winter of 1842, nearby European settlers and missionaries witnessed the so-called Great Eruption. This small-volume outburst created large ash clouds, and mild explosions followed for 15 years. The eruptions of this period were likely phreatic (steam explosions). Josiah Parrish in Champoeg, Oregon witnessed Mount St. Helens in eruption on 22 November 1842. Ash from this eruption may have reached The Dalles, Oregon, 48 miles (80 km) southeast of the volcano.
In October 1843, future California governor Peter H. Burnett recounted a very likely apocryphal story of an Indigenous man who badly burned his foot and leg in lava or hot ash while hunting for deer. The story went that the injured man sought treatment at Fort Vancouver, but the contemporary fort commissary steward, Napoleon McGilvery, disclaimed knowledge of the incident. British lieutenant Henry J. Warre sketched the eruption in 1845, and two years later Canadian painter Paul Kane created watercolors of the gently smoking mountain. Warre's work showed erupting material from a vent about a third of the way down from the summit on the mountain's west or northwest side (possibly at Goat Rocks), and one of Kane's field sketches shows smoke emanating from about the same location.
On April 17, 1857, the Republican, a Steilacoom, Washington, newspaper, reported that "Mount St. Helens, or some other mount to the southward, is seen ... to be in a state of eruption". The lack of a significant ash layer associated with this event indicates that it was a small eruption. This was the first reported volcanic activity since 1854. Before the 1980 eruption, Spirit Lake offered year-round recreational activities. In the summer there was boating, swimming, and camping, while in the winter there was skiing.
Human impact from the 1980 eruption
Fifty-seven people were killed during the eruption. Had the eruption occurred one day later, when loggers would have been at work, rather than on a Sunday, the death toll could have been much higher.
Eighty-three-year-old Harry R. Truman, who had lived near the mountain for 54 years, became famous when he decided not to evacuate before the impending eruption, despite repeated pleas by local authorities. His body was never found after the eruption.
Another victim of the eruption was 30-year-old volcanologist David A. Johnston, who was stationed on the nearby Coldwater Ridge. Moments before his position was hit by the pyroclastic flow, Johnston radioed his famous last words: "Vancouver! Vancouver! This is it!" Johnston's body was never found.
U.S. President Jimmy Carter surveyed the damage and said, "Someone said this area looked like a moonscape. But the moon looks more like a golf course compared to what's up there." A film crew, led by Seattle filmmaker Otto Seiber, was dropped by helicopter on St. Helens on May 23 to document the destruction. Their compasses, however, spun in circles and they quickly became lost. A second eruption occurred on May 25, but the crew survived and was rescued two days later by National Guard helicopter pilots. Their film, The Eruption of Mount St. Helens, later became a popular documentary.
Protection and later history
In 1982, President Ronald Reagan and the U.S. Congress established the Mount St. Helens National Volcanic Monument, a 110,000 acres (45,000 ha) area around the mountain and within the Gifford Pinchot National Forest.
Following the 1980 eruption, the area was left to gradually return to its natural state. In 1987, the U.S. Forest Service reopened the mountain to climbing. It remained open until 2004 when renewed activity caused the closure of the area around the mountain (see Geological history section above for more details).
Most notable was the closure of the Monitor Ridge trail, which previously let up to 100 permitted hikers per day climb to the summit. On July 21, 2006, the mountain was again opened to climbers. In February 2010, a climber died after falling from the rim into the crater.
The mountain is now circled by the Loowit Trail at elevations of 4000–4900 feet (1,200–1,500 m). The northern segment of the trail from the South Fork Toutle River on the west to Windy Pass on the east is a restricted zone where camping, biking, pets, fires, and off-trail excursions are all prohibited.
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