Photos capture Mount St. Helens eruption, the worst U.S. volcanic disaster, 45 years ago.

Mount St. Helens, 45 Years Later

On May 18, 1980, a geologist named Don Swanson dialed his wife with a frantic message, “I’m OK.” Her reply was a plain, unconcerned, “That’s nice.” Little did she know that her husband had spent the morning in an aircraft flying past an erupting volcano.

What Happened?

• 8:32 a.m. Pacific Time, a magnitude 5.1 earthquake rattled Mount St. Helens.
• The quake collapsed the mountain’s conical top into a horseshoe‑shaped crater.
• Rivers of mud and rock poured down the slopes, and a colossal blast of heat and gas blasted the surrounding forest.
• A swarm of ash clouds drifted for over 930 miles, reaching as far as central Montana.

Impact

1. 57 people lost their lives.
2. The eruption was the most destructive volcanic event in U.S. history.
3. It flattened forests, destroyed bridges, and caused more than $1 billion in damage.

Shortly before the eruption, The New York Times described Mount St. Helens as a “relatively little known volcano 50 miles north of Portland, Oregon.” The event forever reshaped the work of volcanologists, geologists, and scientists worldwide.

Remembering the Anniversary

To honor the anniversary of Mount St. Helens’ eruption, a collection of photographs captures the immense devastation that unfolded 45 years ago.

Years earlier, scientists predicted Mount St. Helens would violently erupt.

Mount St. Helens: A Silent Volcano on the Verge of Awakening

Before the 1980 eruption, the volcano’s summit resembled a classic cone that utterly collapsed.

Harry Glicken (USGS); Marli Miller (UCG/Universal Images Group via Getty Images)

Historical Context

• In 1978, the United States Geological Survey (USGS) released a report asserting that Mount St. Helens posed a risk of a violent eruption before the year 2000.
• The volcano’s last documented eruption occurred in 1857.
• Over the past centuries, the period of dormancy—between eruptions—averaged roughly 123 years.
• According to the study, the volcano was merely a matter of time before it resumed activity.

Interpretation

Mount St. Helens was, in 1978, flagged as a potential runaway volcano that could violently erupt before the end of the millennium. It had remained dormant since 1857, with a dormant interval averaging 123 years. It was a fact of time that it would erupt again.

By the spring of 1980, Mount St. Helens had been trembling for weeks.

Mount St. Helens Stirs the Air

On March 27, a burst of steam rolled off the summit, painting the peak a gray‑ashy hue.
The event sparked a coordinated effort to keep the public at a safe distance,
as Liz Westby, a geologist with the USGS Cascades Volcano Observatory, told Business Insider in 2024.
While the volcano could potentially erupt, no definitive conclusion had been drawn.

The March‑April Earthquake Surge

• Thousands of minor quakes cracked the summit in March and April.
• On March 27, steam flushed the snow, revealing a dark‑ash elevation.
• Geologists announced a multi‑agency campaign to shield visitors from the active mountain.

May 18 Collapse and Debris Avalanche

When an earthquake struck on May 18, the volcano’s northern flank caved in.
The collapse triggered a massive debris avalanche that poured enough rock, dirt, and snow to fill a million Olympic‑scale swimming pools.

• Debris surged as far as 14 miles away.
• Ash‑filled plumes rocketed 650 feet into the air.

Capturing a Rare View

People climbed rooftops to snap photos of the steaming summit.
“Everyone really wanted to catch that glimpse of Mount St. Helens,” Westby reflected.

The eruption remains under close observation while scientists monitor the volcano’s evolving activity.

A super-hot mix of rock, gas, and ash caused incredible destruction.

Mount St. Helens’ Cataclysmic Flow Races Down the Volcano

In the heart of Oregon, a pyroclastic flow surged down the flank of Mount St. Helens during a nine‑hour eruption, leaving a scorched trail that spanned nearly the size of Chicago.

What Triggers the Flow?

• Buoyed by a magma‑filled bulge that swelled the north side by about 450 feet, the volcano’s cryptodome fractured.
• Rapid gas expansion produced a devastating blast that exploded sideways, forming the high‑temperature pyroclastic flow.
• The mixture can reach blistering temperatures of 1,500 °F, essentially killing everything in its path.

Speed, Force, and Death

Moving at a heart‑pounding 300 mph, the flow outran the debris avalanche and covered roughly 230 square miles. The relentless heat, force, and high‑speed debris can knock over trees, leaving them stripped and resembling toothpicks.

Ash, Rock, and the Plume

Amid the mountain’s roar, a plume of ash and rock rose as high as 80,000 ft, making the eruption a towering spectacle.

Key Takeaways

• Rapid gas expansion can produce deadly pyroclastic flows.
• The flow outran the debris avalanche, covering an area the size of Chicago.
• Ash and rock lofted an 80,000‑ft plume during the nine‑hour eruption.

Melting snow and ice mixed with rocks and ash turned into mudslides.

Mount St. Helens Volcanic Mudslides Devastated Homes and Infrastructure

In a dramatic May eruption, Mount St. Helens released a torrent of volcanic mudslides known as lahars that engulfed a swath of the surrounding valley.

Key Effects of the Lahars

• Over 200 houses were leveled by the fast-moving mud.
• Major bridges and roads were washed away, cutting off local travel.
• The eruption began when the mountain was still snowcapped; the heat rapidly melted the ice, turning it into a rushing flow of water, rocks, and soil.

Rapid Movement and Scale

The lahars raced at speeds of about 100 miles per hour, tearing through trees and sending a cascade of debris down the valley. Their impact was felt not only by residents but also by the region’s transportation network.

Consequences for Residents

• Local communities lost several hundred homes and endured property losses that will take years to rebuild.
• Families were forced to evacuate as the mudflow threatened downstream areas.

Future Monitoring and Preparedness

Scientists are closely monitoring Mount St. Helens for any signs of renewed activity, emphasizing the need for permanent exacting infrastructure that can mitigate future lahars. The event serves as a stark reminder of the volcanic hazards that can emerge in any snowcapped volcano.

Millions of tons of ash traveled hundreds of miles, closing highways and canceling flights.

Mount St. Helens Ash Folllow

Unexpected Storm Above the Volcano

While at Eastern Washington University, Westby observed a dark streak that she mistook for a thunderstorm. It was ash from the volcanic eruption.

• 520 million tons of ash and volcanic glass drifted into eastern Washington, Idaho, and Montana.
• The ash was so dense that it obscured the sun in several cities.
• Trees were dusted with a fine layer that resembled snow.

Westby’s Observations

Westby described the ash as “fine like baby powder”. Driving through it would stir the particles back into the air.

Aftermath Actions

In the days following the eruption, authorities responded by:

1. Cancelling flights to avoid ash damage to plane engines.
2. Closing highways due to low visibility.

The eruption killed 57 people, including USGS geologist David Johnston.

Mount St. Helens: The Day David Johnston Lost His Life

Only six miles from the volcano, geologist David Johnston was watching Mount St. Helens’ earthquake activity. When the eruption began on May 18, he sent a last radio warning: “Vancouver, this is it.” Shortly after, Johnston died—an event that underscored the need for early monitoring.

Why Early Monitoring Matters

• Geologists see the value of installing sensors before unrest starts.
• Swanson’s memo: “It hit home—we must man red zones early to keep people safe.”
• Westby’s reflection: the lateral blast was more powerful than expected and left many outside the red zone dead.

How Hazard Maps Have Changed

Westby notes that today’s hazard maps are more accurate and consider a broader range of possible eruption outcomes. She says the large burst of the 1980 event still gives us pause, but it has shaped our modern hazard assessment practices.

The eruption destroyed trees and killed wildlife, but many species survived.

The Resurgence of Mount St. Helens

Mount St. Helens erupted, tilting its forest and flipping its fauna. Yet the ecosystem refused to collapse entirely.

Research on Johnston Ridge

• In the first week after the eruption, USDA Forest Service scientists logged the ecological fallout.
• At Johnston Ridge, roughly six miles from the crag, they expected desolation. Instead, they discovered carpenter ants, frogs, pocket gophers, and spiders running their affairs.
• While elk and bears vanished, other flora and fauna slept in sewn snow or slept in burrows.

The Pumice Plain

The blast zone was a hot flow that toppled trees, today christened the pumice plain for its porous volcanic rock. At first, nothing survived here.

• It took two years before researchers uncovered the first plant: the prairie lupine.
• That purple‑flowered perennial is renowned for its resilience.
• Four years after the eruption, new greenery sprouted in the “ghost forests,” where the volcano left broken and dying trees.

A few gophers had a remarkable impact on the volcano’s recovery.

A gopher in an enclosure in 1982.

Michael Allen/UCR

In 1983, scientists realized not much was growing on the lava-scorched regions of Mount St. Helens. They tried an experiment. They flew a few northern pocket gophers to the volcano and put them in enclosures for about 24 hours.They did what gophers do, digging holes. Burrowing into the soil helped aerate it and dispersed bacteria and fungi that promote plant growth.”They’re often considered pests, but we thought they would take old soil, move it to the surface, and that would be where recovery would occur,” University of California, Riverside microbiologist Michael Allen said last year.Little did they know the lasting, positive impacts the gophers’ tunneling would have. After six years, 40,000 plants had sprung up where they’d turned over the soil. The other areas stayed bare.

In the decades since, the environment has drastically changed.

Mount St. Helens Rewilds

New Ecosystem Forms

After the eruption, large mammals have begun to arrive in the blast zone. The Seattle Times reported in 2020 that bear, cougar, elk, and mountain goat have been seen. The absence of larger predators has allowed their prey to flourish, while smaller animals and dormant plants that survived the destruction remain.

Ecologist Perspective

Ecologist Charlie Crisafulli explained to the Seattle Times that Mount St. Helens is not yet back to normal. The pumice plain now starts from scratch, making the ecological situation there unique.

• bears
• cougars
• elk
• mountain goats

The eruption spurred changes to how the US monitors and responds to earthquakes.

USGS Scientists and Mount St. Helens Institute Host Annual Camp for Aspiring Geologists

USGS experts and the Mount St. Helens Institute organize a yearly summer program, inviting middle‑school girls to delve into geological science.

Expanding Research Horizons Beyond Ecology

• Two years after the Mount St. Helens eruption, the USGS founded the Cascades Volcano Observatory, dedicated to David Johnston.
• Only five volcano observatories exist across the United States, making this site a premier laboratory for volcanic study and monitoring.
• The observatory serves as a training ground for the next generation of volcanologists.

GeoGirls: A Field‑Assistant Experience

Westby, in collaboration with the Mount St. Helens Institute, runs the GeoGirls camp each summer for middle‑school girls.

“We treat them as though they were our field assistants, to give them an idea of what it’s like to work on volcanoes,” Westby explained.

Mount St. Helens could erupt again.

Mount St. Helens Remains an Ever‑Active Volcano

Mount St. Helens has continued to erupt after the notorious 1980 event, sending ash clouds and lava flows across the Pacific Northwest. The volcano still shows smaller blasts through 1986, then returned to more intense activity between 2004 and 2008. These eruptions confirm that the mountain will likely erupt again, according to volcano researcher Dr. Eleanor Westby.

Why Mount St. Helens Is the Cascade’s Most Volatile

• Active status – Among all Cascade volcanoes, Mount St. Helens is the most frequently active and the most probable to erupt again.
• Historical pattern – The mountain’s eruptions have followed a clear timeline, supporting future predictions.
• Research depth – Westby’s team monitors seismic and ground‑deformation data to detect impending eruptions.

Techniques That Have Boosted Predictive Power

Since 1980, geological monitoring has evolved dramatically:

• Seismometers – The 1980 network comprised a single seismometer. Today, Westby’s team operates 20 high‑resolution instruments that can record micro‑earthquakes signaling magma movement.
• GPS deformation – Ground‑moving data now alerts scientists if the volcano’s surface is bulging, a key early warning indicator.
• Fast processing software – Modern algorithms convert raw data into actionable insights in seconds, whereas 1980s scientists performed calculations manually.

What Visitors Should Know

Westby advises the public to feel comfortable exploring the Cascades at present. “The volcanoes are safe to be around right now,” she said. “However, you can never predict a future eruption.”

This article was originally published on May 18, 2024 and updated on May 18, 2025. Consult the U.S. Geological Survey for the latest research and safety guidelines.