Mount St. Helens: Forty Years On

written by Sheila G. Miller

While cleaning out our bathroom as a little kid growing up in Portland, Oregon, I came across a pile of hospital face masks. It seemed an odd addition to the usual bathroom detritus. But when you grew up in the Pacific Northwest, Mount St. Helens’ 1980 eruption cast a long shadow. It was good to be prepared.

At 8:32 a.m. on May 18, 1980, an eruption triggered a massive landslide along the entire north face of the mountain. An 80,000-foot eruption column rose into the atmosphere. The top 1,300 feet of the mountain disappeared, replaced by a crater.

Fifty-seven people were killed in the eruption. I was born five days later, and, as a result, I’ve always felt close to the story of Mount St. Helens. This year, on the eve of my fortieth birthday, I thought it was time to learn more about what the eruption truly meant to the region, and what the mountain still holds for us today.

In Steve Olson’s book, Eruption: The Untold Story of Mount St. Helens, he describes the scene. “Fifty-seven people died that Sunday morning—a number that would have been ten times higher if the volcano had exploded on a weekday rather than on a Sunday,” he wrote. “The dead were swept off hillsides, crushed by falling trees, carried away by floods, asphyxiated by ash. The bodies of almost half were never found and remain buried around the mountain.”

The mountain had been threatening to blow for almost two months. Four times, according to Olson’s book, the roadblock along Spirit Lake Highway preventing people from entering a possible blast zone had moved, until it finally was formalized about 12 miles from Spirit Lake. But the roadblock didn’t extend to the many logging and Forest Service roads that ran through the woods nearby. There were plenty of people in the blast zone.

A 5.1-magnitude earthquake was the first sign of an eruption. The result was the largest landslide in recorded history—200 square miles of trees and all life extinguished. A pumice plain developed below the new crater, and nearby Spirit Lake was overtaken by a cloud of ash combined with pumice and lava blocks, snow, ice, pieces of trees and dirt and rocks.

The lake appeared dead—black and bubbling, timber covering the entire surface. The ash cloud traveled around the world, ash landing in almost a dozen states. Layers of ash as much as 3 inches thick settled in places from Eastern Washington to Wyoming.

It was considered the most deadly and economically destructive volcanic eruption in U.S. history. Hundreds of homes were destroyed, as well as dozens of bridges and miles of highway. Four billion board feet of timber were damaged or destroyed by the blast, though much of it was salvaged. Crops were destroyed, as were millions of salmon. Between Seattle and Spokane, I-90 was closed for more than a week. Approximately 26,000 miles of Washington’s highways were considered impassable because of ash buildup.

The eruption was disruptive, messy and deadly enough. But it caused a chain reaction of other issues, as well. For starters, the flooding. The Toutle River was packed with logs and debris and moved swiftly, carrying away buildings and vehicles. Ultimately, according to Olson, the debris streamed 17 miles down the Toutle’s north fork and became a mud flow. Twenty-seven bridges were destroyed. The mud and gravel eventually came to rest on the floors of the Toutle, Cowlitz and Columbia rivers, Olson wrote. “Channels became so clogged that boats could not leave their moorings and future flooding became inevitable. Oceangoing cargo ships were stranded for weeks in Portland, 50 miles south of the volcano, while dredging crews labored to clear a channel through the Columbia.”

By May 24, damages were estimated at $1 billion.

In Rob Carson’s Mount St. Helens: The Eruption and Recovery of a Volcano, he called the eruption both a disaster and an opportunity. “It was a window to the earth, transportation through time to an exotic, primordial era,” he wrote. “Mount St. Helens was the most closely watched, most-photographed, and best scientifically documented volcanic eruption in history.”

Alexa Van Eaton has been a geologist with the USGS since 2015—she started in volcanology in New Zealand, and Mount St. Helens was part of what inspired her to study volcanoes.

“Mount St. Helens in 1980 impacted so many people who observed the ash cloud and were affected by the stories of the fifty-seven people who died and many survivors,” Van Eaton said. “It’s a really important part of the Pacific Northwest and American natural history on a scientific level.”

Richard Wiatt is a research geologist for the Cascades Volcano Observatory. In 1980, he worked for the U.S. Geological Survey and shifted his career in the wake of the Mount St. Helens eruption. He’s focused his work on Mount St. Helens ever since, and wrote a book, In The Path of Destruction: Eyewitness Chronicles of Mount St. Helens.

Wiatt was drawn to collect these people’s stories after his coworker, David Johnston, was killed in the eruption. “That was uncomfortable for quite awhile, partly because what is David’s story? He can’t tell it,” he said.

A couple weeks after the eruption, Wiatt read a piece in a Seattle newspaper about two people who had outrun the pyroclastic flow. He thought talking to them might help him understand more of the science of what had happened, so he met them at a bar on a Friday night. While it was a terrible venue to try to conduct an interview, it was a learning experience.

“Ten minutes in, I realized it didn’t matter how good a geologist I was, I couldn’t figure out from the kind of field methods we use—I could not know how it pounded down with great authority. In the field I can’t tell if the ash was coming sideways or down. That kind of thing intrigued me, and it would really help us understand something about the processes.”

Wiatt sought survivors and others whose accounts revealed more about the science of the eruption.

“Usually people who were in an eruption don’t survive. There aren’t survivors,” he said. “The fact that people did survive, seemingly miraculously—they have a story to tell, and they’re telling that story for scores of other people.”

Wiatt said some survivors reported icy mud balls falling from the sky, as well as hail. While you traditionally think of a volcanic eruption as bringing searingly hot lava and ash, one witness told Wiatt that first he got rained on. “At first he’s wet and cold, he’s freezing even,” he said. “And then the heat wave comes through and fire, one after another. The latter is what is more expected in a volcano.”

Wiatt said the 1980 eruption was unusual. “The mountain didn’t blow its top, the top slid off,” he said. “The missing part is really all in the valley of the North Fork of the Toutle River. It slid off, flowed down the valley and filled that in with up to 400 to 600 feet of crud off the mountain. The old top of the mountain today is in the valley.” That phenomenon helped volcanologists and geologists understand terrains around other long-dormant volcanoes.

The eruption and landslide mowed down oldgrowth forest around Mount St. Helens, and Wiatt remembered visiting Italian volcanologists coming to the overlook to see the destruction. “They couldn’t speak for awhile,” he said. “We could see 1 million downed trees, and they were reminded of Vesuvius— these would all be people.”

Today, the USGS monitors all the area’s volcanoes, but geologists understand that Mount St. Helens is most likely to erupt again.

“What really becomes clear when you visit and look at the ancient deposits is that it is extremely active,” Van Eaton said.

“Just to see how many different layers are squeezed into this tiny time period—the modern-day edifice of Mount St. Helens was all pretty much built up since the pyramids of Giza. It’s one of the most rapidly growing, voluminous strata volcanoes out there in the world.”

Certainly, there would be differences if the mountain were to erupt today—right? Technology, as well as advanced study of the area and the mountain’s behavior would likely provide us with some heads up before a massive eruption.

The Cascades Volcano Observatory was established in the summer of 1980. To Van Eaton, that’s a real sign of how things would be different today if a new eruption took place.

“There is a team of at least fifty scientists dedicated to understanding volcanic processes, and that’s fundamentally different than in 1980,” she said.

“Even though Mount St. Helens is the best-studied volcano in the world, there are still many unanswered questions about the pre-1980 eruptions from Mount St. Helens,” Van Eaton said. “It’s the most active volcano in the Cascades and the most hazardous because of that. It’s been very, very active over the past 4,000 years, so we’re still trying to understand and get a grip on how big some of those earlier eruptions were, what happened. And then, what does that tell us about the nature of future activity?”

The easiest answer is that we can expect more explosive eruptions. “There’s a repertoire of various things that Mount St. Helens can do,” Wiatt said. “It can do concertos and symphonies and chamber music. But you can’t tell ahead of time what’s going to happen.”

Wiatt cautioned that while some preparations for another volcanic eruption would be different in 2020 than in 1980, many aspects wouldn’t change at all.

“People are people,” he said. “If something interesting happens at Mount St. Helens or some other place, there’s not a fence you can put around it to keep people safe. They’re going to get in anyway.”

That happened in 1980, Wiatt said, and it would happen again today. “That kind of pressure from the attitudes in the western United States against authority, that would play out again,” he said. But, he noted, emergency services are much more formalized today than they were in 1980, and he believes an emergency response would be significantly more coordinated.

Today, it would be hard at first blush to see that just forty years ago the area looked like a barren wasteland, rivers clogged with ash and trees flattened against the landscape. Thanks to the natural order, as well as manmade improvements like treeplanting, the area around Mount St. Helens is largely recovered.

“From a geologist’s standpoint, we study things that happened long ago,” Wiatt said. “So this area around Mount St. Helens is settling down into what’s going to be the long-term record. I can imagine a geologist coming in 500 years and saying ‘Gee, I can’t see any effects. It’s pretty spotty.’ But there will be things, no matter how much the trees grow. … No matter how many trees come and go, you’re still going to find traces of this eruption and you’ll be able to say something about what happened here.”