49 Fun Facts About Mount St. Helens

In which US state is Mount St. Helens?

Mount St. Helens is in Washington, in Skamania County, about 50 miles northeast of Portland, Oregon and 96 miles south of Seattle.

On which day of the week did Mount St. Helens erupt on 18 May 1980?

The eruption came at 8:32 am on Sunday, 18 May 1980; because it was a weekend, most loggers were away from the blast zone.

How many people were killed by the 1980 eruption?

The 18 May 1980 eruption killed 57 people, most by asphyxiation from hot ash; the bodies of some victims were never found.

What was the magnitude of the earthquake that triggered the collapse of the mountain's north face?

A magnitude 5.1 earthquake at 8:32 am on 18 May 1980 shook loose the bulging north face, triggering the largest landslide in recorded history.

By roughly how much did the eruption reduce the height of the summit?

The summit dropped about 1,300 feet, from 9,677 to 8,363 feet, leaving a crater open to the north.

What shape is the crater left by the 1980 eruption?

The blast left a horseshoe-shaped crater about a mile wide, its north side breached where the landslide carried the summit away.

What rating did the 1980 eruption receive on the Volcanic Explosivity Index?

The eruption rated 5 on the Volcanic Explosivity Index, a Plinian event that drove ash into the stratosphere and released about 1.5 million tonnes of sulphur dioxide.

How high did the ash plume rise on 18 May 1980?

The column climbed 12 to 16 miles, about 80,000 feet, within 15 minutes, then streamed east at roughly 60 mph and dusted Idaho by noon.

In which Canadian city was ash from the eruption found on cars and roofs the next morning?

High-altitude winds carried fine ash northeast into Canada, and a light dusting settled on cars and rooftops in Edmonton, Alberta, roughly 600 miles from the volcano.

What is the term for the volcanic mudflows that raced down the Toutle and Cowlitz rivers?

Lahars are fast mudflows of volcanic debris and meltwater; those on 18 May 1980 choked the Cowlitz and Columbia rivers, cutting the Columbia's shipping channel from 40 feet to 14 feet deep.

Over roughly what area did the pyroclastic flow flatten vegetation and buildings?

The lateral blast flattened forest across about 230 square miles, killing nearly 7,000 big-game animals and an estimated 12 million hatchery salmon fingerlings.

What was the name of the 83-year-old lodge owner who refused to evacuate and died in the eruption?

Harry R. Truman, 83, had run his lodge on Spirit Lake for more than 50 years and refused to leave; he died in the blast and his body was never found.

What were volcanologist David Johnston's last radioed words from Coldwater Ridge?

David Johnston, 30, radioed 'Vancouver! Vancouver! This is it!' to the USGS office in Vancouver, Washington, seconds before the lateral blast swept his post; Coldwater Ridge was later renamed Johnston Ridge.

How did photographer Robert Landsburg preserve his pictures of the approaching ash cloud?

Robert Landsburg rewound his film, packed the camera in his backpack and lay on top of his backpack to shield the film; his body and the intact film were found on 4 June 1980.

Which US president compared the devastation unfavourably with the surface of the moon?

Jimmy Carter toured the blast zone on 22 May 1980 and said the moon 'looks more like a golf course compared to what's up there'.

What happened to the compasses of the film crew dropped on the mountain on 23 May 1980?

The crew's compasses were useless: they spun in circles, and the lost crew survived a second eruption on 25 May before National Guard helicopters rescued them on 27 May 1980.

What artificial gemstone is made from Mount St. Helens ash?

Helenite is a man-made glass fused from Mount St. Helens ash, usually a vivid green; the ash was also used in ceramic glazes and sold as curios.

After whom did George Vancouver name the mountain in 1792?

Vancouver named it on 20 October 1792 for his friend Alleyne FitzHerbert, Baron St Helens, a British diplomat then serving as ambassador to Spain.

What is the Klickitat name for the mountain, meaning 'smoking or fire mountain'?

The Klickitat called it Louwala-Clough, 'smoking mountain'; in their legend the maiden Loowit was turned into the volcano after the brothers Wy'east and Pahto fought over her.

In the Bridge of the Gods legend, which mountain did the proud suitor Wy'east become?

The proud Wy'east became Mount Hood, south of the Columbia River, while his grieving rival Pahto bowed his head and became a peak to the east.

What nickname did the symmetrical, snow-covered pre-1980 cone earn?

Its graceful symmetry earned it the nickname 'Fujiyama of America'; at 9,677 feet it was Washington's fifth-highest peak before 1980.

How many named glaciers covered the mountain just before the 1980 eruption?

The mountain carried 11 named glaciers before 18 May 1980; the eruption destroyed most of them, though a brand-new Crater Glacier later grew inside the breach.

What split the Crater Glacier into two arms from 2004?

A new lava dome, growing from October 2004, pushed up through the Crater Glacier, splitting it into east and west arms that later crept around the dome and rejoined.

Mount St. Helens is one segment of which Pacific-wide belt of volcanoes?

Mount St. Helens belongs to the Ring of Fire, the chain of volcanoes around the Pacific; it sits in the Cascade Arc, fed by the Juan de Fuca plate subducting beneath North America.

Which Cascade peak, 34 miles to the east, is considered Mount St. Helens's 'brother'?

Mount Adams, 34 miles to the east, is often called St. Helens's 'brother'; both stand about 50 miles from Mount Rainier, the highest Cascade peak.

Which eruptive period, from around 1480, saw the volcano reach its greatest height?

The Kalama period opened around 1480 with an eruption several times larger than 1980's, and by its close about 1647 the summit had reached its greatest height.

The 57-year eruptive period that began in 1800 is named after which feature?

The Goat Rocks period (1800-1857) takes its name from the Goat Rocks dome, a lava dome on the north flank destroyed in the 1980 landslide; it is the first period with both oral and written records.

Which lava type built the domes inside the crater after 1980?

The 1980-86 dome and the 2004-08 extrusion are dacite, a silica-rich, viscous lava that piles up in the crater instead of flowing far.

In 1829 Hall J. Kelley campaigned to rename the entire Cascade chain as what?

Kelley's 1829 scheme would have renamed the Cascades the President's Range, with each major peak named for a US president; St. Helens was to become Mount Washington.

What was the name given to the lava spine extruded from the crater dome in 2004-2005?

Geologists dubbed the smooth spine of dacite the 'whaleback'; its tip broke off on 2 July 2005, and a later feature, half a football field across, was called the slab or fin.

How fast was the 'slab' of cooled rock being pushed upward in 2006?

Through spring 2006 the slab of cooled rock rose at up to 6 feet per day; by mid-June it was crumbling in frequent rockfalls.

In which year did the volcano's continuous activity that began in 2004 finally pause?

In January 2008 steam seeped from a fracture atop the dome, but by month's end lava extrusion had stopped, and in July 2008 the USGS declared the eruption over.

What did President Reagan and Congress establish around the mountain in 1982?

The Mount St. Helens National Volcanic Monument, signed by Reagan on 27 August 1982, protects 110,000 acres inside the Gifford Pinchot National Forest, left to recover naturally.

What is the standard summer climbing route to the crater rim called?

Monitor Ridge, on the south side, is the standard summer route to the rim; Worm Flows is the usual winter route, and a permit is needed above 4,800 feet.

What is the name of the path that circles the mountain at 4,000 to 4,900 feet?

The Loowit Trail, about 28 miles long, circles the volcano between roughly 4,000 and 4,900 feet; its northern stretch through the blast zone bans camping, pets, bikes and fires.

How far did snowmobiler John Slemp fall into the crater in 2008, surviving with minor injuries?

On 15 February 2008 a snow cornice gave way and John Slemp fell 1,500 feet into the crater; he survived with only minor injuries and was rescued by helicopter.

What is the most important ecological concept to emerge from studying the eruption's aftermath?

Ecologists studying the blast zone developed the idea of 'biological legacies': survivors such as buried plants, seeds and dead wood that shaped how life returned.

Which wildflower was the first plant to colonise the barren Pumice Plain?

A single prairie lupine found on the Pumice Plain in 1982 was the first plant to return; as a legume it fixes nitrogen, enriching the sterile pumice for later colonisers.

Which lava tube, about 2.5 miles long, lies on the volcano's south flank?

Ape Cave, a lava tube about 2.5 miles long, formed in a basalt flow roughly 1,900 years ago on the south flank of Mount St. Helens.

What is the average annual rainfall on Mount St. Helens?

Mount St. Helens averages about 140 inches of precipitation a year, and the snowpack on its upper slopes can reach 16 feet.

What is the nearest community to the volcano?

Cougar, a small community in the Lewis River valley about 11 miles south-southwest of the peak, is the nearest settlement to the volcano.

By what local name is State Route 504, the road to the mountain, known?

State Route 504 is the Spirit Lake Memorial Highway, running from Castle Rock to Johnston Ridge; a May 2023 landslide destroyed its Spirit Lake Outlet Bridge and cut off the observatory.

How does the US Geological Survey classify the danger posed by Mount St. Helens?

The USGS's 2018 National Volcanic Threat Assessment rates Mount St. Helens a 'very high threat', second only to Kilauea among US volcanoes.

What did the state designate May as, in memory of the eruption?

Washington designates May as Volcano Awareness Month, marking the 18 May 1980 eruption with events that honour the lives lost and promote volcano preparedness.

How much material did the debris avalanche of 18 May 1980 contain?

The debris avalanche carried about 0.6 cubic miles (2.5 cubic kilometres) of rock and ice, the largest landslide in recorded history.

For how long was Interstate 90 between Seattle and Spokane closed by ash after the 1980 eruption?

Ash closed Interstate 90 between Seattle and Spokane for a week and a half; clearing about 900,000 tons of ash from Washington's highways and airports took ten weeks.

By roughly how much did the 1980 debris avalanche raise Spirit Lake's surface?

The debris avalanche buried the lake bed and dammed the outlet, lifting Spirit Lake's surface by about 200 feet, to roughly 3,400 feet above sea level.

Who took the rapid series of photographs from 11 miles away that let scientists reconstruct the 1980 landslide?

Gary Rosenquist shot a rapid sequence from Bear Meadow, 11 miles northeast; a ridge deflected the blast cloud roughly a mile short of his party's campsite, and they escaped.

Which landslide expert did the USGS consult in April 1980 about the growing bulge on the north face?

Barry Voight, a Penn State landslide expert, warned that the bulging north face could fail; by late April a 1.5-mile section had pushed outward at least 270 feet.