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35 years after Mount St. Helens erupted: A new world of research

The eruption of Mount St. Helens — 35 years ago Monday — coincided with an explosion in digital and cellular technology.

When the volcano erupted on May 18, 1980, the fledgling company Microsoft had just developed the MS-DOS operating system. The online world was still a novelty. Cellphones were unheard of in the United States, and GPS was being developed for aiming missiles.

Volcano research changed so suddenly and dramatically in the decades after the eruption that stories about the old days — when geologists ventured into erupting volcanoes to take measurements with tools as basic as surveyors’ transits and tape measures — seemed like tales from the ancient and almost unbelievable past.

In Vancouver, Washington, the tiny U.S. Geological Survey office where geologists converged in 1980 — working 16-hour days, catnapping in sleeping bags on the floor and feeding on junk food — was replaced by the David A. Johnston Cascades Volcano Observatory, a sophisticated and hushed institution in a suburban office park with a staff of more than 60 full-time employees.

It was no surprise, therefore, that at 2 a.m. on Sept. 23, 2004, when the Earth began trembling a half-mile below Mount St. Helens, geologists noticed the movement immediately.

The flurry of small earthquakes under the volcano grew in frequency and strength, indicating that magma was on its way to the surface.

Geologists at the observatory warned that a new eruption could start explosively. The U.S. Forest Service shut down trails in the Mount St. Helens National Volcanic Monument and closed the mountain to climbers.

Official warnings to stay away from the volcano had the opposite effect, just as they had in 1980.

Sightseers jammed the two-lane Spirit Lake Highway on their way to Johnston Ridge. Daily visits to the monument’s website exceeded 15 million.

At noon on Oct. 1, when the mountain let loose with a burst of steam and ash that rose more than a mile above the crater rim, thousands of people gathered at the observatory cheered.

The volcano sent up several more ash bursts, including one in early 2005 that threw rock fragments as big as bowling balls a mile across the crater.

But after the opening scenes, the drama unfolded slowly and deliberately. For four years, lava in a solid form oozed from a vent in the crater floor, like toothpaste squeezed from a tube.

At first, the lava emerged in a series of smooth-sided spines, thrusting upward to the height of skyscrapers and then crumbling in spectacular rockfalls.

The largest extrusion, a quarter-mile across, resembled a slowly breaching humpback whale. In geologic time, the whale rose at lightning speed — as much as 35 feet a day.

In 16 months, more than 100 million cubic yards of new rock had emerged from the vent, creating a dome larger than the one formed after the 1980 eruption. At its most productive, the lava emerged at the rate of about one dump truck load per second.

If the extrusion had continued at that rate, scientists calculated, it would have filled the crater and restored Mount St. Helens’ perfect cone shape in about 100 years.

The extrusions gradually slowed, though — to about a wheelbarrow load per second — and then stopped in 2008. At that point, 121 million cubic yards of new rock had been deposited in the crater — enough to pave a highway six lanes wide and three feet thick from the mountain all the way across the country to New York City.

Scientists from dozens of fields watched, fascinated, during the slow-motion eruption. Thanks to new technology, they could document it more closely than any eruption in history.

The eruption gave scientists a convenient working laboratory to test theories and develop new monitoring tools.

During the eruption and in the years following, they made new discoveries not only about the mechanics of Mount St. Helens specifically, but also about how volcanoes work in general.

BIG IMPROVEMENTS IN MONITORING

Crowds watch in rapt silence last year during a movie depicting the 1980 eruption of Mt. St. Helens at the Johnston Ridge Observatory. (Dean J. Koepfler, staff file, 2014.)
Crowds watch in rapt silence last year during a movie depicting the 1980 eruption of Mt. St. Helens at the Johnston Ridge Observatory. (Dean J. Koepfler, staff file, 2014.)

The art of volcano monitoring already had improved enormously since 1980.

Satellite-based technology made it possible to detect movements in the Earth in increments of millimeters and to transmit data almost instantaneously from anywhere in the world.

Techniques for measuring seismicity and the subtle landscape changes caused by growing or shrinking reservoirs of magma had been transformed by microelectronics.

Measuring systems were so precise that when the magma stopped flowing in 2008, scientists were able to conclude that the mountain had settled one-half inch due to magma withdrawal beneath it.

With all of the advancements in volcano monitoring, however, basic gaps in knowledge remained.

Scientists were able to detect the underground movement of magma, but they still couldn’t tell what triggered the movement or what its mood might be when it reached the surface.

In 2014, using seismic data and satellite measurements, USGS researchers proved that the magma chamber beneath Mount St. Helens had been growing and recharging since 2008.

But the source of the magma was unclear. They couldn’t tell whether the magma was left over from the eruption that began in 1980, or if it was freshly arriving from a deeper source.

In his office in Vancouver, seismologist Seth Moran pointed to arrow-shaped vectors superimposed on a high-resolution image of the volcano showing movement over time.

The volcano is inflating like a balloon, he said, but the distances are infinitesimally small. It’s likely the arrival of a small amount of additional magma 2.5 to 5 miles beneath the surface is causing the repressurization, Moran said, but nobody can tell for sure.

A seismic monitor measures the vertical and horizontal movement of the ground. (Dean J. Koepfler, staff file, 2014.)
A seismic monitor measures the vertical and horizontal movement of the ground. (Dean J. Koepfler, staff file, 2014.)

“We’ve been looking at what’s beneath the volcano through very fuzzy glasses,” he said. “We have a pretty good idea of what’s happening down to a depth of about 6 miles, but not beyond that.”

The questions that have eluded Earth scientists, he said, are, “How does magma get from the source to the surface, and what controls where volcanoes are?”

To find out, a consortium of research institutions from around the United States and Switzerland began a new series of imaging experiments in 2014.

They were attempting to see with greater clarity the details of how magma makes its way to the crater from the area where tectonic plates collide and the magma is created, some 60 miles beneath the surface.

Does the magma pool in a reservoir at the Earth’s crust? Does it make its way upward in a single, narrow pipelike conduit? Or does it collect in one or more underground ponds along the way?

The results of the yearslong studies should lead to greater understanding of how volcanoes work and eventually to predicting when and how they erupt.

One of the imaging experiments involves setting off a series of underground explosions around the mountain and recording the released energy with thousands of inexpensive portable seismometers.

Such vibrations travel through various rock types and magma at different speeds, making it possible to create subterranean images similar to those created with X-rays and ultrasound.

In addition to the explosive testing, specialists in other disciplines are using broadband seismic receptors for recording natural movements in the Earth.

They’re also examining the magnetic and electrical properties of rock deep beneath the volcano. Electricity moves more freely through magma, making it possible to define its location.

Geologists also are using new chemical techniques to analyze material thrown out of the volcano, hoping that combining data about the composition and ages of the rock will let them piece together a historical account of their movement.

“This still won’t give us anything like 20/20 vision,” Moran said, “but it should make things quite a bit clearer.”

Part of the value of the discoveries made at Mount St. Helens is pure science.

The volcano is a sandbox for scientists. Despite the corporate ambience at the Cascades Volcano Observatory, the geologists who work there clearly are having a ball.

Moran freely admits it. He was only 13 years old when Mount St. Helens erupted, he said, and he’s been fascinated ever since.

“For me as a kid, it was volcanoes and dinosaurs,” he said. “Volcanoes won out.”

DANGERS CLOSE TO HOME

The panoramic and breathtaking view of the south rim of Mount St. Helens, looking past a still venting lava dome last year north toward Spirit Lake and Mount Rainier. (Dean J. Koepfler, staff file, 2014.)
The panoramic and breathtaking view of the south rim of Mount St. Helens, looking past a still venting lava dome last year north toward Spirit Lake and Mount Rainier. (Dean J. Koepfler, staff file, 2014.)

The discoveries scientists are making at Mount St. Helens also have real, practical value: They improve scientists’ ability to predict eruptions, which saves lives.

Mount St. Helens has been the most active volcano in the Cascade Range for the past 4,000 years, and there’s nothing to indicate that will change anytime soon. Scientists expect it to continue to erupt frequently — probably again this century.

Thanks to discoveries at Mount St. Helens, it’s now recognized that other Cascade volcanoes are likely to erupt, too, and that some are potentially even more dangerous.

Of 18 volcanoes in the United States now identified by the USGS as “very high threat,” 10 are in the Cascades — Mount St. Helens, Mount Baker, Mount Rainier, Mount Hood, Crater Lake, Glacier Peak, Mount Shasta, Newberry Volcano, South Sister and Lassen Peak.

After the 1980 eruption of Mount St. Helens, researchers realized the worst threats from the volcanoes are not the eruptions but the giant mudflows, or lahars, they can generate.

Click to enlarge.

Most Cascade volcanoes are well inside national forests or national parks, and their potential blast zones — about 20 miles in any direction — are sparsely populated. But because most are permanently covered with snow and ice, they store enormous quantities of water on their summits.

An eruption on any of the peaks could send slurries of mud surging down river valleys. Most of the rivers that drain the volcanoes flow west toward major population centers, including Tacoma, Seattle and Portland.

Mount Rainier, at 14,410 feet, poses the biggest lahar danger in the Cascade Range.

The 25 named glaciers that drape Rainier have a combined surface area of more than 30 square miles, making it the largest glacial system in the continental United States.

The possible consequences of lahars from Rainier are so extreme it’s considered the most dangerous volcano in America. Rainier hasn’t erupted as often or as violently as St. Helens in the past few thousand years, but it has produced much bigger mudflows.

Recognition of these dangers has caused a significant change in emphasis by volcano researchers.

“There’s been a sea change in the mind of scientists here since Mount St. Helens erupted,” said Carolyn Driedger, a USGS hydrologist at the Cascades Volcano Observatory. “We saw that our involvement couldn’t be just science-for-science’s sake or academic.

“We needed to make a new pact with society, working with public officials, showing people how they can use our science in their communities. And that has happened in a big way. We’ve all spent a lot of time out in the communities. That would not have happened before the 1980s.”

Mount St. Helens was the catalyst for the change, but Driedger said that for her personally, and for many of the scientists she works with, the 1982 eruption of the Mexican volcano El Chichón was even more compelling.

In the weeks leading up to that eruption, the United States provided no technical assistance or expertise to Mexico, she said, despite what scientists had learned at Mount St. Helens.

Nine villages were destroyed in the eruption and 2,000 people died.

Then, in 1985, the Columbian volcano Nevado del Ruiz erupted, killing 23,000 people. Again, she said, the United States was only marginally involved.

“After seeing what happened at El Chichón and Nevado del Ruiz, we recognized that we needed to be more involved,” Driedger said.

GLOBAL USE FOR KNOWLEDGE

Ravaged and deteriorating stumps, victims of a cataclysmic eruption 35 years ago frame a view of Mount St. Helens last year near Johnston Ridge Observatory. (Dean J. Koepfler, staff file, 2014.)
Ravaged and deteriorating stumps, victims of a cataclysmic eruption 35 years ago frame a view of Mount St. Helens last year near Johnston Ridge Observatory. (Dean J. Koepfler, staff file, 2014.)

The knowledge and tools developed at Mount St. Helens are now being shared around the world.

After Nevado del Ruiz, the USGS and the U.S. Agency for International Development put together a team of volcano specialists to provide rapid assistance to other countries in cases of volcanic crisis.

In 1991, when magma began moving toward the surface at Mount Pinatubo in the Philippines, USGS scientists helped predict the volcano’s climactic June 15 eruption, saving an estimated 5,000 lives and $250 million in property.

The outreach extended to local communities, too.

In 2014, Driedger conducted a series of public meetings in communities downstream of Mount Rainier, gently suggesting that their river valleys bear a striking resemblance to areas below Nevado del Ruiz.

“We don’t want to scare people,” she said, “but we do want them to be aware of the hazards.”

Mount St. Helens is credited with sounding another alarm, one that involves airborne ash and the aviation industry. Until the 1980 eruption, no one had recognized that flying through abrasive ash particles could destroy aircraft engines.

One burst of ash that followed the climactic eruption of Mount St. Helens in 1980 was hidden in heavily overcast skies. A C-130 pilot unknowingly flew through the ash plume, and two of his plane’s four turboprop engines died. The pilot landed safely at McChord Air Force Base, but the engines were ruined.

The potential consequences of such encounters were made clear in 2010, when volcanic ash from the eruption of Icelandic volcano Eyjafjallajökull grounded flights in northern Europe for nine days and disrupted air traffic around the world.

“People began to realize there’s no such thing as remote volcanoes anymore,” Driedger said. “You don’t go to a volcano to experience an eruption. It comes to you.”

Permissions line: (c) 2015 by Rob Carson. All rights reserved. Excerpted from Mount St. Helens 35th Anniversary Edition: The Eruption and Recovery of a Volcano by permission of Sasquatch Books.

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