50 Fun Facts About Mount St. Helens

In which US state is Mount St. Helens?

It sits in Skamania County, about 52 miles north-east of Portland and 98 miles south of Seattle.

On which day of the week did the 1980 eruption happen, sparing loggers from the blast zone?

Had it come a day later, the death toll could have been much higher.

How many people were killed by the 1980 eruption?

Because it happened on a weekend, loggers were not at work in the blast zone; the toll could otherwise have been far higher.

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

It struck at 8:32 am and set off the largest debris avalanche in recorded history.

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

The peak went from 9,677 to 8,363 feet, leaving a crater open to the north.

What shape is the crater left by the 1980 eruption?

It is about a mile wide with its north end open in a huge breach.

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

It was classed as a Plinian eruption and released more than 1.5 million tonnes of sulphur dioxide.

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

It erupted vigorously for more than nine hours and moved east at about 60 mph, reaching Idaho by noon.

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

Downwind farms in the eastern part of the state suffered about $100 million of damage.

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

They carried nearly four million cubic yards of material 17 miles into the Columbia River.

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

Nearly 7,000 big-game animals and an estimated 12 million hatchery fish died.

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

He had lived by Spirit Lake since 1929; his body was never found.

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

He was 30; the observatory on the ridge now bears his name.

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

His body and camera were found on 4 June 1980, and the photos gave geologists valuable documentation.

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

He 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?

Lost, the crew survived a second eruption on 25 May and was rescued by National Guard helicopters two days later.

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

The ash was also used for ceramic glazes and sold as a tourist curio.

After whom did George Vancouver name the mountain in 1792?

Alleyne FitzHerbert was a friend of the explorer, who named it as HMS Discovery entered the Columbia's mouth.

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

In their legend the maiden Loowit became the volcano after two rival chiefs fought over her.

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

His rival Pahto, head bowed toward his fallen love, became the sister mountain to the east.

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

Before the eruption it was the fifth-highest peak in its state.

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

Only the Shoestring Glacier revived somewhat afterwards, but a brand-new Crater Glacier grew inside the breach.

What is unusual about the Crater Glacier that formed after the eruption?

Shaded by the crater walls, it grew about 14 feet thicker per year and now surrounds the lava domes.

Mount St. Helens is one segment of which larger geological feature that rings the Pacific?

It sits in the Cascade Volcanic Arc, fed by an oceanic plate subducting beneath North America.

How old is Mount St. Helens, making it geologically young among the Cascade volcanoes?

The summit cone that existed before 1980 began rising only about 2,200 years ago.

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

Both lie about 50 miles from Mount Rainier, the highest of the Cascades.

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

Its opening eruption was several times larger than that of 1980; the period ended around 1647.

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

It is the first period for which both oral and written records exist.

An 1831 eruption tinted the sun bluish-green over Virginia. Who took it as a sign to act?

He interpreted the strange sun of 13 August as the final signal for his rebellion.

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

Each major peak would have taken a president's name; St. Helens was down for the first one.

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

Its tip broke off on 2 July 2005; a later feature, half the size of a football field, was called the slab or fin.

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

By mid-June that year it was crumbling in frequent rockfalls.

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

Steam seeped from a fracture in January of that year, but by month's end no more lava was being extruded.

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

The 110,000-acre area lies within the Gifford Pinchot National Forest.

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

Worm Flows is the usual winter route; 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?

Its northern segment 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?

A snow cornice gave way beneath him; he walked away at the foot of the crater wall.

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

Survivors of the disturbance, from buried plants to organic debris, shaped how life returned.

How many mountain goats were counted on the mountain in 2015, having been wiped out in 1980?

The Cowlitz Indian Tribe, who historically gathered shed goat wool there, helps monitor the recovering herd.

Which animals were reintroduced to wetlands on the mountain's southern flank in May 2026?

The Cowlitz Indian Tribe led the relocation to Pine Creek, one of the last breeding grounds of bull trout there.

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

Snowpack on the upper slopes can reach 16 feet.

What is the nearest community to the volcano?

It sits in the Lewis River valley about 11 miles south-south-west of the peak.

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

A 2023 mudslide destroyed its Spirit Lake Outlet Bridge and cut off the Johnston Ridge Observatory.

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

Geologists expect future eruptions to be larger, since the lava domes need more pressure to burst.

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

Events commemorate the lives lost and discuss volcanic safety.

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

That is about 2.5 cubic kilometres, the largest such slide in recorded history.

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

About 4 to 5 inches of ash fell on Yakima, and clearing roughly 900,000 tons of it from Washington's highways and airports took ten weeks.

Roughly how many bridges were destroyed by the 1980 eruption and its mudflows?

The blast and lahars also wiped out about 200 houses, 15 miles of railway and 185 miles of highway.

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

He and his party survived because local topography deflected the blast about a mile short of their campsite.

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

A USGS team found a 1.5-mile section of the north face had pushed outward by at least 270 feet by late April.