Mount St facts for kids
Quick facts for kids Mount St. Helens |
|
|---|---|
| Louwala-Clough | |
3,000 ft (1 km) steam plume on May 19, 1982, two years after its major eruption
|
|
| Highest point | |
| Elevation | 8,363 ft (2,549 m) |
| Prominence | 4,605 ft (1,404 m) |
| Geography | |
|
Lua error in Module:Location_map at line 420: attempt to index field 'wikibase' (a nil value).
|
|
| Parent range | Cascade Range |
| Topo map | USGS Mount St. Helens |
| Geology | |
| Age of rock | < 40,000 yrs |
| Mountain type | Active stratovolcano |
| Volcanic arc | Cascade Volcanic Arc |
| Last eruption | July 10, 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 is an active stratovolcano in Washington state, USA. It is also known by its Native American names, Louwala-Clough (Cowlitz people) and Loowit (Klickitat people). This volcano is part of the Cascade Range and the Pacific Ring of Fire. It is famous for its ash explosions and fast-moving pyroclastic flows.
Mount St. Helens is most famous for its huge eruption in 1980. This was the deadliest and most damaging volcanic event in US history. Fifty-seven people died. The eruption destroyed 250 homes, 47 bridges, 15 miles (24 km) of railways, and 185 miles (298 km) of highway. An earthquake caused a massive debris avalanche. This avalanche triggered the eruption. The mountain's top dropped from 9,677 feet (2,950 m) to 8,363 feet (2,549 m) high. It left a 1 mile (1.6 km) wide crater shaped like a horseshoe. The Mount St. Helens National Volcanic Monument was created to protect the volcano. It also allows scientists to study what happened after the eruption.
Like most volcanoes in the Cascade Range, Mount St. Helens is a large cone. It is made of lava rock mixed with ash, pumice, and other materials. The mountain has layers of basalt and andesite. Several domes of dacite lava have erupted through these layers. The largest dacite dome formed the old summit. A smaller dome, Goat Rocks, was on its northern side. Both were destroyed in the 1980 eruption.
Contents
Exploring Mount St. Helens
Where is Mount St. Helens?
Mount St. Helens is 34 miles (55 km) west of Mount Adams. It is in the western part of the Cascade Range. These volcanoes are about 50 miles (80 km) from Mount Rainier. Mount Rainier is the tallest Cascade volcano. Mount Hood in Oregon is 60 miles (97 km) southeast of Mount St. Helens.
Mount St. Helens is quite young for a major volcano. It formed in the last 40,000 years. The cone before 1980 started growing about 2,200 years ago. It is the most active volcano in the Cascades in the last 10,000 years.
Before 1980, Mount St. Helens was the fifth-highest peak in Washington. It looked very symmetrical and was covered in snow and ice. This earned it the nickname "Fuji-san of America." The peak rose over 5,000 feet (1,500 m) above its base. The mountain is 6 miles (9.7 km) wide at its base.
Streams flowing from the volcano go into three main rivers. These are the Toutle River, the Kalama River, and the Lewis River. Heavy rain and snow feed these streams. The area gets about 140 inches (3,600 mm) of rain each year. Snow on the upper slopes can be 16 feet (4.9 m) deep. Dams on the Lewis River create hydroelectric power. The Swift Reservoir is directly south of the volcano's peak.
Mount St. Helens is in Skamania County, Washington. But you usually get there through Cowlitz County to the west. State Route 504 connects to Interstate 5 34 miles (55 km) west of the mountain. The closest town is Cougar, 11 miles (18 km) south-southwest of the peak. The Gifford Pinchot National Forest surrounds Mount St. Helens.
Crater Glacier: A Young Ice Giant
Crater Glacier formed during the winter of 1980–1981. It grew quickly because the crater walls shaded it and heavy snow fell. By 2004, it covered about 0.36 square miles (0.93 km2). It was split into two parts by a lava dome. The glacier often looks dark in late summer from falling rocks and ash. In 2006, the ice was about 300 feet (91 m) thick on average. It was up to 650 feet (200 m) deep in some spots. This makes it almost as deep as the much older Carbon Glacier on Mount Rainier. All the ice formed after 1980, making it a very young glacier. Its size is now similar to all the glaciers that were there before 1980.
Since 2004, new volcanic activity has pushed the glacier parts aside and upward. The glacier's surface became very rough, with many cracks and icefalls. This was caused by the movement of the crater floor. The new lava domes have almost completely separated the Crater Glacier into eastern and western parts. Even with the volcanic activity, the glacier's ends have still moved forward. The two parts of the glacier joined in May 2008, completely surrounding the lava domes. New glaciers have also formed on the crater walls above Crater Glacier.
How Mount St. Helens Formed
Early Stages of Growth
Mount St. Helens began forming about 40,000 years ago. This early time is called the "ancestral stages." During these stages, the volcano erupted hot pumice and ash. Large mudflows also flowed down the volcano. These mudflows were a big part of all of St. Helens' eruption cycles. After these early periods, the volcano was quiet for thousands of years. Glaciers also shaped parts of the old cone.
Later periods, like the "Swift Creek Stage," involved more pyroclastic flows and ash spreading across the land. These early eruptions helped build the base of the volcano we see today.
Shaping the Mountain's Form
Around 2500 BCE, the "Smith Creek" period began. Huge amounts of ash and pumice erupted, covering vast areas. An eruption around 1900 BCE was the largest known from St. Helens in the last 10,000 years. Ash from this time reached as far as Banff National Park in Canada.
The "Pine Creek" period followed, with smaller eruptions. Hot pyroclastic flows rushed down the volcano's sides into nearby valleys. Large mudflows also filled parts of the Lewis River valley.
The "Castle Creek" period started around 400 BCE. The lava from St. Helens changed during this time, including new types like olivine and basalt. The cone that existed before the 1980 eruption started to form then. Large lava flows covered parts of the mountain, some traveling many miles. Mudflows also reached the Columbia River.
The "Sugar Bowl" period was short and unique. It produced the only known sideways blast from Mount St. Helens before 1980. The volcano first grew a dome, then erupted violently, sending out ash, blast deposits, and mudflows.
Around 1480, the "Kalama" period began with large eruptions of ash and pumice. The 1480 eruption was several times bigger than the 1980 one. Another large eruption in 1482 was similar in size to the 1980 event. Ash from these eruptions spread far and wide. This period also saw lava flows and pyroclastic flows. Mount St. Helens reached its greatest height and perfect shape by the end of the Kalama period, around 1647.
The "Goat Rocks" period started in 1800. This is the first time we have both spoken stories and written records about eruptions. Like the Kalama period, it began with an ash explosion, followed by lava flow, and ended with a dome forming. The 1800 eruption was likely as big as the 1980 one, but it didn't destroy the cone. Ash from it reached Montana. Many small ash eruptions were reported from 1831 to 1857. The Goat Rocks dome was where the bulge formed in the 1980 eruption. It was completely destroyed on May 18, 1980.
Mount St. Helens: Recent Activity
The 1980 Eruption and Its Aftermath
On March 20, 1980, Mount St. Helens had a magnitude 4.2 earthquake. On March 27, steam started coming out. By late April, the north side of the mountain began to bulge.
On May 18, a magnitude 5.1 earthquake hit. This caused a huge part of the mountain's north face to collapse. It was the biggest debris avalanche ever recorded. The magma inside burst out in a large pyroclastic flow. This flow flattened trees and buildings over 230 square miles (600 km2). Over 1.5 million metric tons of sulfur dioxide went into the air. On the Volcanic Explosivity Index, this eruption was a five, known as a Plinian eruption.
The collapsing north side mixed with ice, snow, and water. This created lahars (volcanic mudflows). The lahars flowed many miles down the Toutle River and Cowlitz Rivers. They destroyed bridges and logging camps. About 3,900,000 cubic yards (3,000,000 m3) of material traveled 17 miles (27 km) south into the Columbia River.
For over nine hours, a strong ash plume erupted. It reached 12 to 16 miles (20 to 27 km) above sea level. The plume moved east at about 60 miles per hour (97 km/h). Ash reached Idaho by noon. The next morning, ash was found on cars and roofs as far away as Edmonton, Canada.
By 5:30 p.m. on May 18, the ash column got smaller. Smaller eruptions continued for several days. The May 18 eruption released a huge amount of heat energy. It ejected over 0.67 cubic miles (2.8 km3) of material. The loss of the north side reduced St. Helens' height by about 1,300 feet (400 m). It left a crater 1 to 2 miles (1.6 to 3.2 km) wide and 0.5 miles (0.80 km) deep. The eruption killed 57 people. It also killed nearly 7,000 large animals and 12 million fish. Over 200 homes, 185 miles (298 km) of highway, and 15 miles (24 km) of railways were destroyed.
Between 1980 and 1986, Mount St. Helens remained active. A new lava dome grew inside the crater. Many small explosions and dome-building eruptions happened. From 1989 to 1991, the mountain erupted with large ash clouds several times.
Activity from 2004 to 2008
Magma reached the surface around October 11, 2004. This led to a new lava dome growing on the south side of the old dome. This new dome kept growing through 2005 and 2006. Scientists saw unusual features, like a "whaleback" lava spine. This was a long shaft of hardened magma pushed up by pressure from below. These features were fragile and broke apart quickly. On July 2, 2005, the whaleback's tip broke off. This caused a rockfall that sent ash and dust hundreds of meters into the air.
.jpg)
Mount St. Helens showed a lot of activity on March 8, 2005. A 36,000-foot (11,000 m) plume of steam and ash appeared. It was visible from Seattle. This small eruption was a release of pressure from the growing dome. A magnitude 2.5 earthquake happened at the same time.
Another feature that emerged was called the "fin" or "slab." This large, cooled volcanic rock was about half the size of a football field. It was being pushed upward as fast as 6 feet (1.8 m) per day. By mid-June 2006, the slab was crumbling. But it was still being pushed out. The dome's height was 7,550 feet (2,300 m).
On October 22, 2006, a magnitude 3.5 earthquake caused Spine 7 to break off. The collapse sent an ash plume 2,000 feet (610 m) over the crater rim. The plume quickly disappeared.
On December 19, 2006, a large white plume of steam was seen. Some media thought it was a small eruption. However, the Cascades Volcano Observatory did not report a big ash plume. The volcano had been erupting continuously since October 2004. This eruption was mostly a slow pushing out of lava, forming a dome in the crater.
On January 16, 2008, steam started leaking from a crack on top of the lava dome. The earthquakes linked to this were the most significant since 2004. Scientists stopped working in the crater and on the mountain's sides. But the risk of a major eruption was low. By the end of January, the eruption paused. No more lava was coming out of the dome. On July 10, 2008, it was decided that the eruption had ended. This was after more than six months of no volcanic activity.
Mount St. Helens: A Look at Human History
Native American Stories and Importance
American Indian stories explain the eruptions of Mount St. Helens and other Cascade volcanoes. The most famous is the Bridge of the Gods legend from the Klickitat people. In their story, the chief of all gods and his two sons, Pahto and Wy'east, traveled down the Columbia River. They found a beautiful area now called The Dalles. The sons argued over the land. Their father shot two arrows, one north and one south. Pahto followed the north arrow, and Wy'east followed the south. The chief built the Bridge of the Gods so his family could meet.
When the two sons fell in love with a maiden named Loowit, she couldn't choose. The sons fought over her, destroying villages and forests. The earth shook so hard that the huge bridge fell into the river. This created the cascades of the Columbia River Gorge.
As punishment, the chief turned the lovers into great mountains where they fell. Wy'east became Mount Hood. Pahto became Mount Adams. The fair Loowit became Mount St. Helens. The Klickitats called it Louwala-Clough, meaning "smoking or fire mountain."
The mountain is also very important to the Cowlitz and Yakama tribes. They call it "Lawetlat'la," meaning "the smoker." It is important in their creation stories, songs, and rituals. Because of its cultural importance, over 12,000 acres (4,900 ha) of the mountain are listed on the National Register of Historic Places.
Early European Sightings and Exploration
Royal Navy Commander George Vancouver and his crew first saw Mount St. Helens on May 19, 1792. They were exploring the northern Pacific Ocean coast. Vancouver named the mountain after British diplomat Alleyne Fitzherbert, 1st Baron St Helens on October 20, 1792.
Years later, explorers and traders heard about an erupting volcano. Geologists later figured out that an eruption happened in 1800. This started the 57-year Goat Rocks Eruptive Period. The Nespelem tribe, alarmed by "dry snow," danced and prayed. They suffered from hunger that winter.
In 1805 and 1806, members of the Lewis and Clark Expedition saw Mount St. Helens. But they didn't report any ongoing eruptions. They did mention clogged river channels near Portland. This suggested an eruption from Mount Hood decades earlier.
In 1829, Hall J. Kelley tried to rename the Cascade Range the "President's Range." He wanted to name each major mountain after a US President. In his plan, Mount St. Helens would have been named Mount Washington.
European Settlement and Use
The first confirmed eyewitness report of an eruption was in March 1835. Meredith Gairdner, working for the Hudson's Bay Company, sent a report. James Dwight Dana of Yale University saw the quiet peak in 1841.
In late 1842, settlers saw the "Great Eruption." This small eruption created large ash clouds. Mild explosions continued for 15 years. These were likely steam explosions. Ash from the November 1842 eruption may have reached The Dalles, Oregon.
In 1843, Peter Hardeman Burnett told a story about a Native American man. The man supposedly burned his foot in lava while hunting. British lieutenant Henry J. Warre sketched an eruption in 1845. Two years later, Canadian painter Paul Kane painted the smoking mountain. Their art showed smoke coming from the mountain's side.
On April 17, 1857, a newspaper reported Mount St. Helens erupting. This was the first activity reported since 1854. It was a small eruption, as there was no significant ash layer.
Before the 1980 eruption, Spirit Lake was a popular spot for fun. People enjoyed boating, swimming, and camping in summer. In winter, they went skiing.
The Human Impact of the 1980 Eruption
Fifty-seven people died during the eruption. If the eruption had happened on a workday, more loggers would have been there, and the death toll would have been much higher.
83-year-old Harry R. Truman lived near the mountain for 54 years. He became famous for refusing to leave before the eruption. His body was never found.
Another victim was 30-year-old volcanologist David A. Johnston. He was stationed on Coldwater Ridge. Moments before the pyroclastic flow hit, Johnston radioed his last words: "Vancouver! Vancouver! This is it!" His body was never found either.
U.S. President Jimmy Carter saw the damage. He said the area looked like a "moonscape," but the moon looked more like a golf course compared to it. A film crew was dropped by helicopter on May 23 to film the destruction. Their compasses went wild, and they got lost. A second eruption happened on May 25, but the crew survived. They were rescued two days later. Their film, The Eruption of Mount St. Helens, became a popular documentary.
Protecting the Volcano and Its Future
In 1982, President Ronald Reagan and the U.S. Congress created the Mount St. Helens National Volcanic Monument. This protected 110,000 acres (45,000 ha) around the mountain.
After the 1980 eruption, the area was left to heal naturally. In 1987, the U.S. Forest Service reopened the mountain for climbing. It stayed open until 2004, when new activity caused closures. On July 21, 2006, the mountain reopened for climbers. In February 2010, a climber died after falling into the crater.
The Loowit Trail now circles the mountain at elevations of 4,000–4,900 feet (1,200–1,500 m). The northern part of the trail is a restricted zone. Camping, biking, pets, fires, and off-trail trips are not allowed there.
Climbing and Outdoor Fun
Mount St. Helens is a popular spot for mountaineers, both beginners and experts. People climb the peak all year. But it's most popular from late spring to early fall. All routes have steep, rough sections.
You need a permit to climb above 4,800 feet (1,500 m) on Mount St. Helens. This permit system has been in place since 1987.
The most common route in warmer months is the Monitor Ridge Route. It starts at the Climbers Bivouac. This is the most popular and crowded way to the summit in summer. It gains about 4,600 feet (1,400 m) in about 5 miles (8.0 km) to reach the crater rim. It's a tough climb but doesn't need special technical skills. Most climbers finish the round trip in 7 to 12 hours.
The Worm Flows Route is the usual winter route. It's the most direct way to the summit. This route gains about 5,700 feet (1,700 m) in elevation over about 6 miles (9.7 km). It doesn't require the technical climbing skills needed for other Cascade peaks like Mount Rainier. The "Worm Flows" name comes from the rocky lava flows around the route. You can reach this route from the Marble Mountain Sno-Park.
Images for kids
-
David A. Johnston hours before he was killed by the eruption
