Mount St. Helens

Mount St. Helens
MSH82 st helens plume from harrys ridge 05-19-82.jpg
3,000 ft (0.9 km) high steam plume on May 19, 1982, two years after the major eruption
Highest point
Elevation8,363 ft (2,549 m)
Prominence4,605 ft (1,404 m)
  • Washington prominent peaks 11th
  • Washington isolated peaks 11th
  • Washington highest peaks 35th
Coordinates46°11′28″N 122°11′40″W / 46.1912000°N 122.1944000°W / 46.1912000; -122.1944000Coordinates:46°11′28″N 122°11′40″W / 46.1912000°N 122.1944000°W / 46.1912000; -122.1944000[1]
EtymologyLord St Helens
Native name
Mount St. Helens is located in Washington (state)
Mount St. Helens
Mount St. Helens
Location in Washington state
Parent rangeCascade Range
Topo mapUSGS Mount St. Helens
Age of rock< 40,000 yrs
Mountain typeActive stratovolcano (Subduction zone)
Volcanic arcCascade Volcanic Arc
Last eruption2004–2008
First ascent1853 by Thomas J. Dryer
Easiest routeHike 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 the British diplomat Lord 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.

Mount St. Helens is best known for its major eruption on May 18, 1980, 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 ft (2,950 m) to 8,363 ft (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. By six years after the eruption, most lakes in the area returned to their normal state.[9]

After its 1980 eruption, the volcano had continuous volcanic activity until 2008. Geologists predict that future eruptions will be more destructive, since the configuration of the lava domes there require more pressure to erupt.[10] Despite this, 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 U.S President Ronald Reagan and the U.S Congress.

Geographic setting and description


A large conical volcano.
Mount St. Helens pictured the day before the 1980 eruption, which removed much of the northern face of the mountain, leaving a large crater

Mount St. Helens is 34 miles (55 km) west of Mount Adams, in the western part of the Cascade Range. Considered "brother and sister" mountains, the two volcanoes are approximately 50 miles (80 km) from Mount Rainier, the highest of the Cascade volcanoes. Mount Hood, the nearest major volcanic peak in Oregon, is 60 miles (100 km) 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.[11] The volcano is considered the most active in the Cascades within the Holocene epoch, which encompasses roughly the last 10,000 years.[12]

Prior to the 1980 eruption, Mount St. Helens was the fifth-highest peak in Washington. It stood out prominently from surrounding hills because of the symmetry and extensive snow and ice cover of the pre-1980 summit cone, earning it the nickname, by some, "Fuji-san of America".[13]: 201  The peak rose more than 5,000 feet (1,500 m) above its base, where the lower flanks merge with adjacent ridges. The mountain is 6 miles (9.7 km) across at its base, which is at an elevation of 4,400 feet (1,300 m) on the northeastern side and 4,000 feet (1,200 m) elsewhere. At the pre-eruption tree line, the width of the cone was 4 miles (6.4 km).

Streams that originate on the volcano enter three main river systems: The Toutle River on the north and northwest, the Kalama River on the west, and the Lewis River on the south and east. The streams are fed by abundant rain and snow. The average annual rainfall is 140 inches (360 cm), and the snowpack on the mountain's upper slopes can reach 16 feet (4.9 m). The Lewis River is impounded by three dams for hydroelectric power generation. The southern and eastern sides of the volcano drain into an upstream impoundment, the Swift Reservoir, which is directly south of the volcano's peak.

Although Mount St. Helens is in Skamania County, Washington, access routes to the mountain run through Cowlitz County to the west, and Lewis County to the north. State Route 504, locally known as the Spirit Lake Memorial Highway, connects with Interstate 5 at Exit 49, 34 miles (55 km) to the west of the mountain.[14]: 297  That north–south highway skirts the low-lying cities of Castle Rock, Longview and Kelso along the Cowlitz River, and passes through the Vancouver, WashingtonPortland, Oregon metropolitan area less than 50 miles (80 km) to the southwest. The community nearest the volcano is Cougar, Washington, in the Lewis River valley 11 miles (18 km) south-southwest of the peak. Gifford Pinchot National Forest surrounds Mount St. Helens.

Crater Glacier and other new rock glaciers

During the winter of 1980–1981, a new glacier appeared. Now officially named Crater Glacier, it was formerly known as the Tulutson Glacier. Shadowed by the crater walls and fed by heavy snowfall and repeated snow avalanches, it grew rapidly (14 feet (4.3 m) per year in thickness). By 2004, it covered about 0.36 square miles (0.93 km2), and was divided by the dome into a western and eastern lobe. Typically, by late summer, the glacier looks dark from rockfall from the crater walls and ash from eruptions. As of 2006, the ice had an average thickness of 300 feet (100 m) and a maximum of 650 feet (200 m), nearly as deep as the much older and larger Carbon Glacier of Mount Rainier. The ice is all post-1980, making the glacier very young geologically. However, the volume of the new glacier is about the same as all the pre-1980 glaciers combined.[15][16][17][18][19]

With the recent volcanic activity starting in 2004, the glacier lobes were pushed aside and upward by the growth of new volcanic domes. The surface of the glacier, once mostly without crevasses, turned into a chaotic jumble of icefalls heavily criss-crossed with crevasses and seracs caused by movement of the crater floor.[20] The new domes have almost separated the Crater Glacier into an eastern and western lobe. Despite the volcanic activity, the termini of the glacier have still advanced, with a slight advance on the western lobe and a more considerable advance on the more shaded eastern lobe. Due to the advance, two lobes of the glacier joined in late May 2008 and thus the glacier completely surrounds the lava domes.[20][21][22] In addition, since 2004, new glaciers have formed on the crater wall above Crater Glacier feeding rock and ice onto its surface below; there are two rock glaciers to the north of the eastern lobe of Crater Glacier.[23]


Climate data for Mount St. Helens Summit. 1991-2020
Average high °F (°C)30.0
Daily mean °F (°C)25.1
Average low °F (°C)20.2
Average precipitation inches (mm)27.00
Average dew point °F (°C)18.7
Source: PRISM Climate Group[24]


Mount St. Helens is part of the Cascades Volcanic Province, an arc-shaped band extending from southwestern British Columbia to Northern California, roughly parallel to the Pacific coastline.[25] Beneath the Cascade Volcanic Province, a dense oceanic plate sinks beneath the North American Plate; a process known as subduction (geology). As the oceanic slab sinks deep into the Earth's interior beneath the continental plate, high temperatures and pressures allow water molecules locked in the minerals of solid rock to escape. The water vapor rises into the pliable mantle above the subducting plate, causing some of the mantle to melt. This newly formed magma ascends upward through the crust along a path of least resistance, both by way of fractures and faults as well as by melting wall rocks. The addition of melted crust changes the geochemical composition. Some of the melt rises toward the Earth's surface to erupt, forming the Cascade Volcanic Arc above the subduction zone.[26]

The magma from the mantle has accumulated in two chambers below the volcano: one approximately 5–12 kilometres (3–7 mi) below the surface, the other about 12–40 kilometres (7–25 mi).[27] The lower chamber may be shared with Mount Adams and the Indian Heaven volcanic field.[28]

Ancestral stages of eruptive activity

The early eruptive stages of Mount St. Helens are known as the "Ape Canyon Stage" (around 40,000–35,000 years ago), the "Cougar Stage" (ca. 20,000–18,000 years ago), and the "Swift Creek Stage" (roughly 13,000–8,000 years ago).[29] The modern period, since about 2500 BCE, is called the "Spirit Lake Stage". Collectively, the pre–Spirit Lake stages are known as the "ancestral stages". The ancestral and modern stages differ primarily in the composition of the erupted lavas; ancestral lavas consisted of a characteristic mixture of dacite and andesite, while modern lava is very diverse (ranging from olivine basalt to andesite and dacite).[13]: 214 

St. Helens started its growth in the Pleistocene 37,600 years ago, during the Ape Canyon stage, with dacite and andesite eruptions of hot pumice and ash.[13]: 214  Thirty-six thousand years ago a large mudflow cascaded down the volcano;[13]: 214  mudflows were significant forces in all of St. Helens' eruptive cycles. The Ape Canyon eruptive period ended around 35,000 years ago and was followed by 17,000 years of relative quiet. Parts of this ancestral cone were fragmented and transported by glaciers 14,000–18,000 years ago during the last glacial period of the current ice age.[13]: 214 

The second eruptive period, the Cougar Stage, started 20,000 years ago and lasted for 2,000 years.[13]: 214  Pyroclastic flows of hot pumice and ash along with dome growth occurred during this period. Another 5,000 years of dormancy followed, only to be upset by the beginning of the Swift Creek eruptive period, typified by pyroclastic flows, dome growth and blanketing of the countryside with tephra. Swift Creek ended 8,000 years ago.

Smith Creek and Pine Creek eruptive periods

A dormancy of about 4,000 years was broken around 2500 BCE with the start of the Smith Creek eruptive period, when eruptions of large amounts of ash and yellowish-brown pumice covered thousands of square miles.[13]: 215  An eruption in 1900 BCE was the largest known eruption from St. Helens during the Holocene epoch, depositing the Yn tephra.[13]: 215 [30] This eruptive period lasted until about 1600 BCE and left 18 inches (46 cm) deep deposits of material 50 miles (80 km) distant in what is now Mount Rainier National Park. Trace deposits have been found as far northeast as Banff National Park in Alberta, and as far southeast as eastern Oregon.[13]: 215  All told there may have been up to 2.5 cubic miles (10 km3) of material ejected in this cycle.[13]: 215  Some 400 years of dormancy followed.

St. Helens came alive again around 1200 BCE — the Pine Creek eruptive period.[13]: 215  This lasted until about 800 BCE and was characterized by smaller-volume eruptions. Numerous dense, nearly red hot pyroclastic flows sped down St. Helens' flanks and came to rest in nearby valleys. A large mudflow partly filled 40 miles (64 km) of the Lewis River valley sometime between 1000 BCE and 500 BCE.

Castle Creek and Sugar Bowl eruptive periods

The next eruptive period, the Castle Creek period, began about 400 BCE, and is characterized by a change in the composition of St. Helens' lava, with the addition of olivine and basalt.[13]: 216  The pre-1980 summit cone started to form during the Castle Creek period. Significant lava flows in addition to the previously much more common fragmented and pulverized lavas and rocks (tephra) distinguished this period. Large lava flows of andesite and basalt covered parts of the mountain, including one around the year 100 BCE that traveled all the way into the Lewis and Kalama river valleys.[13]: 216  Others, such as Cave Basalt (known for its system of lava tubes), flowed up to 9 miles (14 km) from their vents.[13]: 216  During the first century, mudflows moved 30 miles (50 km) down the Toutle and Kalama river valleys and may have reached the Columbia River. Another 400 years of dormancy ensued.

The Sugar Bowl eruptive period was short and markedly different from other periods in Mount St. Helens history. It produced the only unequivocal laterally directed blast known from Mount St. Helens before the 1980 eruptions.[31] During Sugar Bowl time, the volcano first erupted quietly to produce a dome, then erupted violently at least twice producing a small volume of tephra, directed-blast deposits, pyroclastic flows, and lahars.[31]

Kalama and Goat Rocks eruptive periods

Painting of a rolling landscape with a conical mountain in background.
The symmetrical appearance of St. Helens prior to the 1980 eruption earned it the nickname "Mount Fuji of America". The once familiar shape was formed out of the Kalama and Goat Rocks eruptive periods.

Roughly 700 years of dormancy were broken in about 1480, when large amounts of pale gray dacite pumice and ash started to erupt, beginning the Kalama period. The eruption in 1480 was several times larger than the May 18, 1980 eruption.[31] In 1482, another large eruption rivaling the 1980 eruption in volume is known to have occurred.[31] Ash and pumice piled 6 miles (9.7 km) northeast of the volcano to a thickness of 3 feet (0.9 m); 50 miles (80 km) away, the ash was 2 inches (5 cm) deep. Large pyroclastic flows and mudflows subsequently rushed down St. Helens' west flanks and into the Kalama River drainage system.

This 150-year period next saw the eruption of less silica-rich lava in the form of andesitic ash that formed at least eight alternating light- and dark-colored layers.[13]: 216  Blocky andesite lava then flowed from St. Helens' summit crater down the volcano's southeast flank.[13]: 216  Later, pyroclastic flows raced down over the andesite lava and into the Kalama River valley. It ended with the emplacement of a dacite dome several hundred feet (~200 m) high at the volcano's summit, which filled and overtopped an explosion crater already at the summit.[13]: 217  Large parts of the dome's sides broke away and mantled parts of the volcano's cone with talus. Lateral explosions excavated a notch in the southeast crater wall. St. Helens reached its greatest height and achieved its highly symmetrical form by the time the Kalama eruptive cycle ended, in about 1647.[13]: 217  The volcano remained quiet for the next 150 years.

The 57-year eruptive period that started in 1800 was named after the Goat Rocks dome and is the first time that both oral and written records exist.[13]: 217  Like the Kalama period, the Goat Rocks period started with an explosion of dacite tephra, followed by an andesite lava flow, and culminated with the emplacement of a dacite dome. The 1800 eruption probably rivaled the 1980 eruption in size, although it did not result in massive destruction of the cone. The ash drifted northeast over central and eastern Washington, northern Idaho, and western Montana. There were at least a dozen reported small eruptions of ash from 1831 to 1857, including a fairly large one in 1842. (The 1831 eruption is likely what tinted the sun bluish-green in Southampton County, Virginia on the afternoon of August 13 — which Nat Turner interpreted as a final signal to launch the United States' largest slave rebellion.[32]) The vent was apparently at or near Goat Rocks on the northeast flank.[13]: 217  Goat Rocks dome was the site of the bulge in the 1980 eruption, and it was obliterated in the major eruption event on May 18, 1980, that destroyed the entire north face and top 1,300 feet (400 m) of the mountain.

Modern eruptive period

Ash cloud erupting from volcano
Mount St. Helens erupted on May 18, 1980, at 08:32 PDT.

1980 to 2001 activity

On March 20, 1980, Mount St. Helens experienced a magnitude 4.2 earthquake;[4] and, on March 27, steam venting started.[33] By the end of April, the north side of the mountain had started to bulge.[34] On May 18, a second earthquake, of magnitude 5.1, triggered a massive collapse of the north face of the mountain. It was the largest known debris avalanche in recorded history. The magma in St. Helens burst forth into a large-scale pyroclastic flow that flattened vegetation and buildings over 230 square miles (600 km2). More than 1.5 million metric tons of sulfur dioxide were released into the atmosphere.[35] On the Volcanic Explosivity Index scale, the eruption was rated a 5, and categorized as a Plinian eruption.

The collapse of the northern flank of St. Helens mixed with ice, snow, and water to create lahars (volcanic mudflows). The lahars flowed many miles down the Toutle and Cowlitz Rivers, destroying bridges and lumber camps. A total of 3,900,000 cubic yards (3,000,000 m3) of material was transported 17 miles (27 km) south into the Columbia River by the mudflows.[13]: 209 

For more than nine hours, a vigorous plume of ash erupted, eventually reaching 12 to 16 miles (20 to 27 km) above sea level.[36] The plume moved eastward at an average speed of 60 miles per hour (100 km/h) with ash reaching Idaho by noon. Ashes from the eruption were found collecting on top of cars and roofs the next morning as far as the city of Edmonton in Alberta, Canada.

By about 5:30 p.m. on May 18, the vertical ash column declined in stature, and less severe outbursts continued through the night and for the next several days. The St. Helens May 18 eruption released 24 megatons of thermal energy;[6][37] it ejected more than 0.67 cubic miles (2.79 km3) of material.[6] The removal of the north side of the mountain reduced St. Helens' height by about 1,300 feet (400 m) and left a crater 1 mile (1.6 km) to 2 miles (3.2 km) wide and 0.4 miles (600 m) deep, with its north end open in a huge breach. The eruption killed 57 people, nearly 7,000 big game animals (deer, elk, and bear), and an estimated 12 million fish from a hatchery.[5] It destroyed or extensively damaged over 200 homes, 185 miles (298 km) of highway, and 15 miles (24 km) of railways.[5]

Between 1980 and 1986, activity continued at Mount St. Helens, with a new lava dome forming in the crater. Numerous small explosions and dome-building eruptions occurred. From December 7, 1989, to January 6, 1990, and from November 5, 1990, to February 14, 1991, the mountain erupted with sometimes huge clouds of ash.[38]

2004 to 2008 activity

Large fairly smooth rock structure inside a crater
Appearance of the "Whaleback" in February 2005

Magma reached the surface of the volcano about October 11, 2004, resulting in the building of a new lava dome on the existing dome's south side. This new dome continued to grow throughout 2005 and into 2006. Several transient features were observed, such as a lava spine nicknamed the "whaleback", which comprised long shafts of solidified magma being extruded by the pressure of magma beneath. These features were fragile and broke down soon after they were formed. On July 2, 2005, the tip of the whaleback broke off, causing a rockfall that sent ash and dust several hundred meters into the air.[39]

Mount St. Helens showed significant activity on March 8, 2005, when a 36,000-foot (11,000 m) plume of steam and ash emerged — visible from Seattle.[40] This relatively minor eruption was a release of pressure consistent with ongoing dome building. The release was accompanied by a magnitude 2.5 earthquake.

Another feature to emerge from the dome was called the "fin" or "slab". Approximately half the size of a football field, the large, cooled volcanic rock was being forced upward as quickly as 6 ft (2 m) per day.[41][42] In mid-June 2006, the slab was crumbling in frequent rockfalls, although it was still being extruded. The height of the dome was 7,550 feet (2,300 m), still below the height reached in July 2005 when the whaleback collapsed.

On October 22, 2006, at 3:13 PM PST, a magnitude 3.5 earthquake broke loose Spine 7. The collapse and avalanche of the lava dome sent an ash plume 2,000 feet (600 m) over the western rim of the crater; the ash plume then rapidly dissipated.

On December 19, 2006, a large white plume of condensing steam was observed, leading some media people to assume there had been a small eruption. However, the Cascades Volcano Observatory of the USGS did not mention any significant ash plume.[43] The volcano was in continuous eruption from October 2004, but this eruption consisted in large part of a gradual extrusion of lava forming a dome in the crater.

On January 16, 2008, steam began seeping from a fracture on top of the lava dome. Associated seismic activity was the most noteworthy since 2004. Scientists suspended activities in the crater and the mountain flanks, but the risk of a major eruption was deemed low.[44] By the end of January, the eruption paused; no more lava was being extruded from the lava dome. On July 10, 2008, it was determined that the eruption had ended, after more than six months of no volcanic activity.[45]

Future hazards

Future eruptions of Mount St. Helens will likely be even larger than the 1980 eruption.[14]: 296  The current configuration of lava domes in the crater means that much more pressure will be required for the next eruption, and hence the level of destruction will be higher.[14]: 296  Significant ashfall may spread over 40,000 square miles (100,000 km2), disrupting transportation.[14]: 296  A large lahar flow is likely on branches of the Toutle River, possibly causing destruction in inhabited areas along the I-5 corridor.[46]


Twenty years after the 1980 eruption, dead trees caused by the blast are still standing.

In its undisturbed state, the slopes of Mount St. Helens lie in the Western Cascades Montane Highlands ecoregion.[47] This ecoregion has abundant precipitation: an average of 93.4 inches (2,373 mm) of precipitation falls each year at Spirit Lake.[48] This precipitation supported dense forest up to 5,200 feet (1,600 m), with western hemlock, Douglas-fir, and western redcedar. Above this, this forest was dominated by Pacific silver fir up to 4,300 feet (1,300 m). Finally, below treeline, the forest consisted of mountain hemlock, Pacific silver fir and Alaska yellow cedar.[48] Large mammals included Roosevelt elk, black-tailed deer, American black bear, and mountain lion.[48]

Treeline at Mount St Helens was unusually low, at about 4,400 feet (1,340 m). This was due to prior volcanic disturbance of the forest: the treeline was thought to be moving up the slopes before the eruption.[48] Alpine meadows were uncommon at Mount St Helens.[48] Mountain goats inhabited higher elevations of the peak, although they were wiped out in the 1980 eruption.[49]

Ecological disturbance caused by eruption

The Mount St. Helens eruption has the most ecological study of any eruption, because research into disturbance commenced immediately after the eruption, and because the eruption did not sterilize the immediate area. More than half of the papers on ecological response to volcanic eruption came from studies at Mount St. Helens[50]

The most important ecological concept that came from the study at Mount St. Helens is biological legacy.[51] Biological legacies are the survivors of catastrophic disturbance: they can either be alive (e.g., plants that survive ashfall or pyroclastic flow), organic debris, or biotic patterns left over from before the disturbance.[52] These biological legacies highly influence the re-establishment of the post-disturbance ecology.[51][53]

Human history

Mt St. Helens before the 1980 eruption (taken from Spirit Lake)
Indigenous American legends were inspired by the volcano's beauty.

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.[54]

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.[54]

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.[55]

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).[56]

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.[57] 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.[58]

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.[58]

Exploration by Europeans

Man by wooden building that has six fur pelts on it.
19th-century photo of a fur trapper working in the Mount St. Helens area

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,[56][59] 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).[13]: 217  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.[13]: 217 

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.[60] 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.[61]

European colonization and use of the area

Painting of a conical volcano erupting at night from the side.
Painting by Paul Kane Mount St. Helens erupting at night after his 1847 visit to 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.[13]: 219  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.[62]

In the 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.[13]: 220–221  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.[12]

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.[13]: 224  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.[13]: 225, 227 

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".[13]: 228  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.[13]: 228 

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

Man sitting at a campsite
David A. Johnston hours before he was killed by the eruption

Fifty-seven people were killed during the eruption.[63] 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.[64] His body was never found after the eruption.[65]

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!"[66] Johnston's body was never found.[67]

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."[68] 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.

The eruption had negative effects beyond the immediate area of the volcano. Ashfall caused approximately $100 million of damage to agriculture downwind in Eastern Washington.[69]

The eruption also had positive impacts on society. Apple and wheat production were higher in the 1980 growing season, possibly due to ash helping to retain moisture in the soil.[70] The ash was also a source of income: it was the raw material for the artificial gemstone helenite,[71] or for ceramic glazes,[72] or sold as a tourist curio.[73]

Protection and later history

View of the hillside at the Johnston Ridge Observatory (named for David A. Johnston), 16 July 2016, 36 years after the eruption, showing recovering plant growth

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.[74]

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.[75] In February 2010, a climber died after falling from the rim into the crater.[76]

Climbing and recreation

Mount St. Helens is a popular climbing destination for both beginning and experienced mountaineers. The peak is climbed year-round, although it is more often climbed from late spring through early fall. All routes include sections of steep, rugged terrain.[77] A permit system has been in place for climbers since 1987. A climbing permit is required year-round for anyone who will be above 4,800 feet (1,500 m) on the slopes of Mount St. Helens.[78]

The standard hiking/mountaineering route in the warmer months is the Monitor Ridge Route, which starts at the Climbers Bivouac. This is the most popular and crowded route to the summit in the summer and gains about 4,600 feet (1,400 m) in approximately 5 miles (8 km) to reach the crater rim.[79] Although strenuous, it is considered a non-technical climb that involves some scrambling. Most climbers complete the round trip in 7 to 12 hours.[80]

The Worm Flows Route is considered the standard winter route on Mount St. Helens, as it is the most direct route to the summit. The route gains about 5,700 feet (1,700 m) in elevation over about 6 miles (10 km) from trailhead to summit but does not demand the technical climbing that some other Cascade peaks like Mount Rainier do. The route name refers to the rocky lava flows that surround the route.[81] This route can be accessed via the Marble Mountain Sno-Park and the Swift Ski Trail.[82]

The mountain is now circled by the Loowit Trail at elevations of 4,000–4,900 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.[83][84]

On April 14, 2008, John Slemp, a snowmobiler from Damascus, Oregon, fell 1,500 feet into the crater after a snow cornice gave way beneath him on a trip to the volcano with his son. Despite his long fall, Slemp survived with minor injuries, and was able to walk after coming to a stop at the foot of the crater wall, where he was rescued by a mountain rescue helicopter.[85]

A visitor center run by the Washington State Parks is in Silver Lake, Washington, about 30 miles (48 km) west of Mount St. Helens.[86] Exhibits include a large model of the volcano, a seismograph, a theater program, and an outdoor natural trail.[86]

Panoramic view from the summit of Mount St. Helens as seen in October 2009. Climbers stand on the crater rim and are visible along the Monitor Ridge climbing route.

See also



  1. ^ a b c "Mount Saint Helens". Geographic Names Information System. United States Geological Survey.
  2. ^ "Distance between Portland and Mount Saint Helens". Retrieved 27 March 2021.
  3. ^ "Distance between Seattle and Mount Saint Helens". Retrieved 27 March 2021.
  4. ^ a b "Mount St. Helens National Volcanic Monument". USDA Forest Service. Archived from the original on 23 November 2006.
  5. ^ a b c Tilling, Robert I; Topinka, Lyn; Swanson, Donald A (1990). "Impact and Aftermath". Eruptions of Mount St. Helens: Past, Present, and Future. 1.01. USGS.
  6. ^ a b c "Mount St. Helens – From the 1980 eruption to 2000". United States Geological Survey. 2000. Fact Sheet 036-00. Retrieved 12 November 2006.
  7. ^ "May 18, 1980 eruption of Mount St. Helens". USDA Forest Service. Archived from the original on 29 May 2009.
  8. ^ "1980 Cataclysmic Eruption". Mount St. Helens. USGS. Retrieved 27 March 2021.
  9. ^ "Mount St. Helens: A Living Laboratory for Ecological Research | Pacific Northwest Research Station | PNW - US Forest Service". Retrieved 1 June 2021.
  10. ^ 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.
  11. ^ Mullineaux, D.R.; Crandell, D.R. (1981). The 1980 eruptions of Mount St. Helens, Washington (Report). United States Geological Survey. p. 3. Professional Paper 1250. Retrieved 28 October 2006.
  12. ^ a b "Description of Mount St. Helens". USGS. Retrieved 15 November 2006.
  13. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac Harris, Stephen L. (1988). "Mount St. Helens: A living fire mountain". Fire Mountains of the West: The Cascade and Mono Lake volcanoes (1st ed.). Missoula, Montana: Mountain Press Publishing Company. pp. 201–228. ISBN 0-87842-220-X.
  14. ^ a b c d Harris, Stephen L. (2005). "Mount St. Helens: A living fire mountain". Fire Mountains of the West: The Cascade and Mono Lake volcanoes (3rd ed.). Missoula, Montana: Mountain Press Publishing Company. pp. 201–228. ISBN 0-87842-511-X.
  15. ^ Brugman, Melinda M.; Post, Austin (1981). "Effects of volcanism on the glaciers of Mount St. Helens": 22. USGS Circular 850-D. Retrieved 7 March 2007. {{cite journal}}: Cite journal requires |journal= (help)
  16. ^ Wiggins, Tracy B.; Hansen, Jon D.; Clark, Douglas H. (2002). "Growth and flow of a new glacier in Mount St. Helens Crater". Abstracts with Programs. Geological Society of America. 34 (5): 91.
  17. ^ Schilling, Steve P.; Carrara, Paul E.; Thompson, Ren A.; Iwatsubo, Eugene Y. (2004). "Posteruption glacier development within the crater of Mount St. Helens, Washington, USA". Quaternary Research. Elsevier Science (USA). 61 (3): 325–329. Bibcode:2004QuRes..61..325S. doi:10.1016/j.yqres.2003.11.002. S2CID 128528280.
  18. ^ McCandless, Melanie; Plummer, Mitchell; Clark, Douglas (2005). "Predictions of the growth and steady-state form of the Mount St. Helens Crater Glacier using a 2-D glacier model". Abstracts with Programs. Geological Society of America. 37 (7): 354.
  19. ^ Schilling, Steve P.; Ramsey, David W.; Messerich, James A.; Thompson, Ren A. (8 August 2006). "Rebuilding Mount St. Helens". USGS Scientific Investigations Map 2928. Retrieved 7 March 2007.
  20. ^ a b Volcano Review (PDF) (Report). US Forest Service. Archived from the original (PDF) on 26 June 2008.
  21. ^ Schilling, Steve (30 May 2008). MSH08 aerial: New dome from north 30 May 2008 (photo). United States Geological Survey. Archived from the original on 26 June 2008. Retrieved 7 June 2008. – Glacier is still connected south of the lava dome.
  22. ^ Schilling, Steve (30 May 2008). MSH08 aerial: St. Helens crater from north 30 May 2008 (photo). United States Geological Survey. Archived from the original on 26 June 2008. Retrieved 7 June 2008. – Glacier arms touch on North end of glacier.
  23. ^ Haugerud, R.A.; Harding, D.J.; Mark, L.E.; Zeigler, J.; Queija, V.; Johnson, S.Y. (December 2004). Lidar measurement of topographic change during the 2004 eruption of Mount St. Helens, WA. American Geophysical Union, Fall Meeting. Vol. 53. p. 1. Bibcode:2004AGUFM.V53D..01H.
  24. ^ "PRISM Climate Group, Oregon State University". Retrieved 12 January 2022.
  25. ^ "Pacific – Cascades Volcanic Province". Archived from the original on 23 September 2006. Retrieved 13 March 2021. Public Domain This article incorporates text from this source, which is in the public domain.
  26. ^ "Pacific – Cascades Volcanic Province". Archived from the original on 24 September 2006. Public Domain This article incorporates text from this source, which is in the public domain.
  27. ^ Hand, Eric (4 November 2015). "Deep magma chambers seen beneath Mount St. Helens". Science. doi:10.1126/science.aad7392.
  28. ^ McKinnon, Mika (10 November 2015). "Mount Saint Helens May Share Magma with an Entire Field of Volcanoes". Gizmodo.
  29. ^ "Mount St. Helens – Summary of Volcanic History". USDA Forest Service. Archived from the original on 11 October 2008.
  30. ^ Pallister, John S.; Clynne, Michael A.; Wright, Heather M.; Van Eaton, Alexa R.; Vallance, James W.; Sherrod, David R.; Kokelaar, B. Peter (2017). "Eruptive history". Field-Trip Guide to Mount St. Helens, Washington: An overview of the eruptive history and petrology, tephra deposits, 1980 proclastic density current deposits, and the crater. Scientific Investigations Report. United States Department of the Interior. p. 11. ISSN 2328-0328.
  31. ^ a b c d Mullineaux, Donal R (1996). "Pre-1980 tephra-fall deposits erupted from Mount St. Helens, Washington". USGS. Professional Paper 1563. Retrieved 15 November 2006. {{cite journal}}: Cite journal requires |journal= (help)
  32. ^ Breen, Patrick H. (2005). Nat Turner's revolt: rebellion and response in Southampton County, Virginia. Retrieved 21 November 2021.
  33. ^ "Summary of Events Leading Up to the May 18, 1980, eruption of Mount St. Helens: March 22–28". USDA Forest Service. Archived from the original on 13 November 2007.
  34. ^ "Summary of Events Leading Up to the May 18, 1980 Eruption of Mount St. Helens: April 26–May 2". USDA Forest Service. Archived from the original on 13 November 2007.
  35. ^ "Emission of sulfur dioxide gas from Mount St. Helens, 1980–1988". United States Geological Survey. 25 September 2008. Retrieved 25 March 2009.
  36. ^ Kiver, Eugene P; Harris, David V (1999). Geology of U.S. parklands (5th ed.). Wiley. p. 149. ISBN 9780471332183.
  37. ^ "Mount St. Helens National Volcanic Monument". United States Forest Service. Archived from the original on 29 May 2009. 24 megatons thermal energy
  38. ^ Myers, Bobbie (1992). "Small explosions interrupt 3 year quiescence at Mount St. Helens, Washington". Earthquakes and Volcanoes. 23 (2): 58–73. Archived from the original on 30 December 2006. Retrieved 26 November 2006 – via
  39. ^ "Before and after images". USGS. Archived from the original on 3 September 2005.
  40. ^ "Mount St. Helens, Washington – 'Plume in the Evening'". USGS. 8 March 2005. Archived from the original on 11 March 2005. Retrieved 15 November 2006.
  41. ^ "New slab growing in Mount St. Helens dome". Fox News. Archived from the original on 26 October 2012. Retrieved 6 December 2010.
  42. ^ "Rock Slab Growing at Mt. St. Helens Volcano". Astronomy Picture of the Day. 9 May 2006.
  43. ^ "In the News". Cascades Volcano Observatory. Archived from the original on 7 January 2007. Retrieved 4 January 2007.
  44. ^ "Small quake reported at Mount St. Helens". USA Today. 17 January 2008. Retrieved 6 December 2010.
  45. ^ "Mount St. Helens, Washington – Eruption 2004 to current". USGS. Archived from the original on 6 October 2008. Retrieved 6 October 2008.
  46. ^ "Volcanic Hazards at Mount St. Helens". USGS. Retrieved 15 March 2021.
  47. ^ Pater, D; Bryce, SA; Kagan, J; et al. "Ecoregions of Western Washington and Oregon" (PDF). Retrieved 26 March 2021. color poster with map, descriptive text, summary tables, and photographs; with a Reverse side {{cite web}}: External link in |quote= (help)
  48. ^ a b c d e Swanson, FJ; Crisafulli, CM; Yamaguchi, DK (2005). "Geological and Ecological Settings of MountSt. Helens Before May 18, 1980". In Dale, VH; Swanson, FJ; Crisafulli, CM (eds.). Ecological Responses to the 1980 Eruption of Mount St. Helens (PDF). Springer. doi:10.1007/0-387-28150-9. ISBN 978-0-387-23868-5.
  49. ^ Gilfillan, Jule (30 June 2017). "Counting Mountain Goats On Mount St. Helens". Oregon Public Broadcasting.
  50. ^ Dale, VH; Swanson, FJ; Crisafulli, CM (2005). "Disturbance, Survival, and Succession: Understanding Ecological Responses to the 1980 Eruption of Mount St. Helens". In Dale, VH; Swanson, FJ; Crisafulli, CM (eds.). Ecological Responses to the 1980 Eruption of Mount St. Helens (PDF). pp. 3–11. doi:10.1007/0-387-28150-9. ISBN 978-0-387-23868-5.
  51. ^ a b Franklin, JF (2005). "Reconfiguring Disturbance, Succession, and Forest Management: The Science of Mount St. Helens". In Dale, VH; Swanson, FJ; Crisafulli, CM (eds.). Ecological Responses to the 1980 Eruption of Mount St. Helens (PDF). pp. 3–11. doi:10.1007/0-387-28150-9. ISBN 978-0-387-23868-5.
  52. ^ Franklin, JF (1990). "Biological Legacies: A Critical Management Concept from Mount St. Helens" (PDF). Trans. 55' N. A. Wildl. & Nat. Res. Conf.: 216–219.
  53. ^ Walker, LR; Sikes, DS; DeGange, AR; Jewett, SC; et al. (2013). "Biological legacies: Direct early ecosystem recovery and food web reorganization after a volcanic eruption in Alaska". Écoscience. 20 (3): 240–251. doi:10.2980/20-3-3603. S2CID 86156161.
  54. ^ a b Satterfield, Archie (2003). Country Roads of Washington. iUniverse. p. 82. ISBN 0-595-26863-3.
  55. ^ "The Bridge of the Gods". Archived from the original on 20 July 2006. Retrieved 26 November 2006.{{cite web}}: CS1 maint: unfit URL (link)
  56. ^ a b "Volcanoes and history: Cascade Range volcano names". USGS. Archived from the original on 28 October 2006. Retrieved 20 October 2006.
  57. ^ "Lawetlat'la". Retrieved 16 July 2021.
  58. ^ a b "NRHP nomination form and supplementary listing record for Lawetlat'la [Mount St. Helens]" (PDF). National Park Service. Retrieved 30 October 2013.
  59. ^ Vancouver, George (1798). A Voyage of Discovery to the North Pacific Ocean, and Round the World. London, UK. pp. 421–422. OCLC 54529835. OL 24592146M.
  60. ^ Pringle 1993.
  61. ^ Meany, Edmond S. (1920). "Origin of Washington Geographic Names". The Washington Historical Quarterly. Washington University State Historical Society. XI: 211–212. Retrieved 11 June 2009.
  62. ^ "The Volcanoes of Lewis and Clark". USGS. Retrieved 15 November 2006.
  63. ^ Grisham, Lori (17 May 2015). "'I'm going to stay right here.' Lives lost in Mount St. Helens eruption". USA Today. Archived from the original on 3 June 2021. Retrieved 20 June 2021.
  64. ^ Kean, Sam (12 December 2018). "Harry versus the volcano". Science History Institute. Sam Kean. Retrieved 29 May 2021.{{cite web}}: CS1 maint: url-status (link)
  65. ^ "Sister, friend say Harry probably dead". Spokane Daily Chronicle. Associated Press. 20 May 1980.
  66. ^ Cartier, Kimberly (27 June 2019). "Perish the thought: A life in science sometimes becomes a death, too". Eos. Archived from the original on 10 June 2021. Retrieved 20 June 2021.
  67. ^ "Workers may have found body of man buried by volcanic ash". Moscow-Pullman Daily News. 29 June 1993.
  68. ^ "Mount St. Helens: Senator Murray Speaks on the 25th Anniversary of the May 18, 1980 Eruption". U.S. Senate. Retrieved 12 November 2006.
  69. ^ Cook, RJ; Barron, JC; Papendick, RI; Williams, GJ, III (2 January 1981). "Impact on Agriculture of the Mount St. Helens Eruptions". Science. 211 (4477): 16–22. Bibcode:1981Sci...211...16C. doi:10.1126/science.211.4477.16. PMID 17731222.
  70. ^ "Impact and aftermath". USGS. 25 June 1997.
  71. ^ "What is Helenite?". Sciencing.
  72. ^ Hval, Cindy (12 June 2015). "Potter turns ash into beauty". Spokane Spokesman-Review.
  73. ^ "Mount St. Helens Gift Shop". Retrieved 13 March 2021.
  74. ^ "Mount St. Helens National Volcanic Monument: General visitor information". USDA Forest Service. Archived from the original on 21 November 2004. Retrieved 12 November 2006.
  75. ^ "Climbing Mount St. Helens". USDA Forest Service. Archived from the original on 19 October 2004. Retrieved 12 November 2006.
  76. ^ "Climber dies after rescue attempts fail on Mount St. Helens". 17 February 2010. Archived from the original on 21 July 2011.
  77. ^ "Climbing Mount St. Helens". U.S. Forest Service. Retrieved 28 February 2014.
  78. ^ "Mount St Helens Climbing Permit System". U.S. Forest Service. Retrieved 28 February 2014.
  79. ^ "Monitor Ridge". Retrieved 28 February 2014.
  80. ^ "Monitor Ridge Climbing Route". U.S. Forest Service. Retrieved 28 February 2014.
  81. ^ "Worm Flows Route, Mount St. Helens". The Peak Seeker. Retrieved 17 February 2016.
  82. ^ "The Worm Flows, Winter Climbing Route". U.S. Forest Service. Retrieved 28 February 2014.
  83. ^ "Loowit Trail". Retrieved 3 September 2011.
  84. ^ "Mount St. Helens Volcanic National Monument: Restricted Area" (PDF). USDA Forest Service. Retrieved 3 September 2011.
  85. ^ Hwa Song, Jung (16 April 2008). "Man Survives 1,500-Ft. Drop Down Mt. St. Helens". ABC News. Retrieved 15 March 2021.{{cite web}}: CS1 maint: url-status (link)
  86. ^ a b "Mount St. Helens Visitor Center". Washington State Parks. Retrieved 19 January 2016.


Further reading

  • "Eruption of Mount St. Helens". National Geographic. Vol. 159, no. 1. January 1981. pp. 3–65. ISSN 0027-9358. OCLC 643483454.

External links

Media files used on this page

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, Licence: PD

A red triangle with a thick white border.

The Matterhorn as seen from Zermatt.png
Author/Creator: Buaidh, Licence: CC BY-SA 4.0
The Matterhorn as seen from Zermatt. This is a square crop of Peak of the Matterhorn, seen from Zermatt, Switzerland.jpg
Mount St. Helens, one day before the devastating eruption.jpg
This slide shows Mount St. Helens, one day before the devastating eruption. The view is from Johnston Ridge, six miles (10 kilometers) northwest of the volcano.
St Helens before 1980 eruption horizon fixed.jpg
USFS Photograph taken before 18 May 1980 by Jim Nieland, US Forest Service, Mount St Helens National Volcanic Monument.
Spaccato vulcano.svg
Author/Creator: Fred the Oyster, Licence: CC BY-SA 4.0
Illustration of volcano eruption
Mount St Helens Summit Pano II.jpg
Author/Creator: Gregg M. Erickson (talk · contribs), Licence: CC BY 3.0
360° panorama from the summit of Mount St. Helens as seen on an early-October afternoon. In the foreground is the ice-covered crater rim. Visible in the lower center is the lava dome. Steam rises from several dome vents. Above the dome, in the upper center, lie Mount Rainier and Spirit Lake. Mount Adams appears to the right of Rainier on the horizon as well as Mount Hood and Mount Jefferson on the far right. Also on the far right are glimpses of the Swift Reservoir, Yale Lake, Lake Merwin and the Lewis River. Climbers stand on the crater rim and are visible along the Monitor Ridge climbing route. Photo by Gregg M. Erickson
MSH82 st helens plume from harrys ridge 05-19-82.jpg
Plumes of steam, gas, and ash often occurred at Mount St. Helens in the early 1980s. On clear days they could be seen from Portland, Oregon, 50 mi (80 km) to the south. The plume photographed here rose nearly 3,000 ft (910 m) above the volcano's rim. The view is from Harrys Ridge, 5 mi (8 km) north of the mountain.
1890 Clohessy and Strengele engraving of Mount St Helens (cropped).jpg
Detail from engraving of Portland, Oregon, with Mount St. Helens in background. A "Bird's-eye-view" of Portland, Oregon in 1890. Original lithograph shows Mount St. Helens, Mount Adams, and Mount Hood, with the Columbia River and the Willamette River. Reference #75694939.
Tree snags at Mount St. Helens.jpg
Mount St. Helens, located in Washington State, erupted catastrophically on May 18, 1980. When the north side of the volcano collapsed, pressure was released on hot water within the volcano. The hot water burst into steam and blasted out the new opening in a powerful lateral blast. A hot stone-filled wind surged north at speeds over 300 miles per hour and temperatures of 660 °F. This lateral blast toppled or snapped off trees over a 230-square-mile area north of the volcano, which later became known as the "blowdown zone." On the outer fringes of the blowdown zone, the force of the lateral blast had diminished and trees remained standing but were seared by the hot air, leaving a band of standing dead trees referred to as the "scorch zone."

View of a portion of land on Johnston Ridge, one mile north from Mount St. Helens. The ridge was engulfed by the hot pyroclastic flow from the 1980 eruption which obliterated all plant and animal matter. Thirty-six years later, the region has begun to recover with new tree and plant growth as well as the recolonization of the region by animals.
Abies lasiocarpa 0775.JPG
Author/Creator: Walter Siegmund (talk), Licence: CC BY-SA 3.0
Subalpine Fir forest; McClure Rock (left center, just above forested slopes; 7385 feet)
MSH80 eruption mount st helens 05-18-80.jpg
On May 18, 1980, at 8:32 a.m. Pacific Daylight Time, a magnitude 5.1 earthquake shook Mount St. Helens. The bulge and surrounding area slid away in a gigantic rockslide and debris avalanche, releasing pressure, and triggering a major pumice and ash eruption of the volcano. Thirteen-hundred feet (400 meters) of the peak collapsed or blew outwards. As a result, 24 square miles (62 square kilometers) of valley was filled by a debris avalanche, 250 square miles (650 square kilometers) of recreation, timber, and private lands were damaged by a lateral blast, and an estimated 200 million cubic yards (150 million cubic meters) of material was deposited directly by lahars (volcanic mudflows) into the river channels. Sixty-one people were killed or are still missing. USGS Photograph taken on May 18, 1980, by Austin Post.
USA Washington relief location map.jpg
Author/Creator: Carport, Licence: CC BY-SA 3.0
Physical location map of Washington, USA
Cascade Range plate tectonics-en.svg
Author/Creator: User:Surachit, Licence: CC BY 3.0
Plate tectonics of the Cascade Range