10 Years Later, Mt. St. Helens Is a Living Textbook on Volcano Science

At 4.1 on the Richter scale, the earthquake on the afternoon of March 20, 1980, was no great shakes. It knocked snow off the north face of Mt. St. Helens but went virtually unnoticed in the surrounding counties of southwestern Washington.

Nearly 130 miles to the north, the line traced by a wandering pencil on a seismograph at the University of Washington was first interpreted as evidence of a tremor 75 miles southeast of the dormant volcano.

But on closer inspection, seismologists determined that the quake had occurred under the mountain, and relatively close to the surface.

It was the first recorded sign that Mt. St. Helens’ volcanic fuse was lit. One week later, on March 27, the volcano belched steam and ash in its first eruption in 123 years. The accompanying 4.7-magnitude quake sent seismic needles skittering.

Fifty-two days after that, on May 18, 1980, the mountain exploded spectacularly. The eruption killed 57 people and sent ash around the world. In an instant, 1,300 feet of the mountain disappeared, fully a fifth of its towering majesty simply blown away.

The smoking, raw-edged crater left behind stunned residents of Washington and Oregon used to gazing out at a symmetrical, snowcapped peak.

“It woke people up to the fact that having a volcano in your back yard can be dangerous,” said Dwight Crandell, who is retired from the U.S. Geological Survey. In 1978, Crandell helped write a report that predicted an eruption at Mt. St. Helens this century.

The blast was also a wake-up call for volcanologists around the world. In the 1970s, only two countries with volcanic mountains were examining the dangers of nearby human settlements. Today 16 countries have active studies under way, Crandell said by telephone from his home in Denver.

“It’s clear that the 1980 eruption was a sensation for the science of volcanology,” said geologist Steve Brantley, stationed at the USGS Cascade Volcano Observatory in Vancouver, Wash., about 45 miles southwest of Mt. St. Helens. About 80 scientists work at the observatory, built after the eruption.

University seismologist Steve Malone said the March 20 earthquake was strong enough to draw attention to the area but not so unusual as to make scientists suspicious that molten rock was squeezing into crevices deep under the earth.

“Earthquakes at the volcano are not unheard of,” Malone said. “They generate a bit of interest but not immediate alarm.”

But quakes kept coming, increasing in number and strength. Three days after the initial quake, university seismologists warned the USGS about a “potentially serious situation.”

“This was when we first suspected we might be on to something other than just a small earthquake swarm,” Malone said.

Teams of geologists arrived to set up equipment to monitor ground movement and the gases emitted each time the volcano burped. Seismologists stayed close to their machines. The Forest Service began warning people to stay clear of the mountain because of avalanches.

But the scientists were not working in isolation. Scores of eager newspaper and broadcast reporters joined the crush. Researchers accustomed to working in geologic time, in a science where more is unknown than known, were being asked to provide instant answers for that evening’s news and the next morning’s newspapers.

“I remember . . . being a bit overwhelmed by the media interest this was already generating,” Malone said. “All we had was data and some possibilities and a lot of questions.”

Meantime, the ground was moving at postcard-perfect Spirit Lake, at the mountain’s foot. Chuck Tonn, who ran the Forest Service desk at the lake, hung a pencil from a string to show the faint shaking. The lake was evacuated Tuesday morning, March 25.

“I was glad to leave that morning,” Tonn said. “That last night, I don’t think any of us slept. It seemed like there was always some movement going on.”

Not everyone left. Harry Truman, the 83-year-old owner and keeper of rustic Spirit Lake Lodge, dug in his heels. Truman said he would stay on the mountain that had been his home for 50 years, the mountain that eight weeks later would kill him. In the media catering to the nation’s rising anticipation, Truman became a cantankerous folk hero.

Another local, Stan Lee, 67, owner of the Kid Valley Store about 20 miles from the peak, snorted at talk of a possible eruption and accused the Forest Service of plotting to squelch development. Two days later, the mountain blew.

That first eruption shot a black plume almost a mile and a half high. By mid-April, the stark gray and brown hollow of a crater had replaced the mountain’s snowy point, once 9,677 feet above sea level. Ash falls in the region were commonplace, with fickle winds determining who got dusted next.

May 18, 1980, the day the mountain finally blew its top, is now designated Eruption Day in Geological Survey books. On those who were there and experienced the power and awe and terror, Mt. St. Helens has left its mark as clearly as the eruption scarred the landscape.

“I feel fortunate to have been at Mt. St. Helens from the beginning all these 10 years,” said Tonn, who now manages the Forest Service’s visitors’ center west of the 110,000-acre National Volcanic Monument.

“It kind of puts me in my place. It puts me in awe of what can happen.”

For Crandell and fellow USGS geologist Donal Mullineaux, the eruption was right on time. After studying dormant Cascade Range volcanoes in the 1960s and 1970s, they predicted in 1978 that Mt. St. Helens would likely erupt relatively soon.

“Everything we found indicated it was a very young volcano, and a very explosive volcano, and a frequently active volcano,” which last erupted in 1857, Crandell said. “We felt almost sure the volcano would erupt, and sooner rather than later. That is what the history told us.”

While some public officials greeted their hazard report seriously, there were also snickers, the two scientists said. “A lot of people made fun of it, of course,” Mullineaux said.

Crandell said he was gratified that many countries with volcanoes have since made use of their work in hazard assessment, including New Zealand, Japan, Italy, Mexico, Ecuador and Colombia.

The eruption of Colombia’s Nevado del Ruiz in November of 1985 provides an example of how hazard assessment could have helped, Crandell said. An assessment had been completed, and hazard zones had been laid out, including likely flood and mud-flow zones at the town of Armero. But word never reached local officials. There were no evacuations, and 25,000 people perished.

Mt. St. Helens prompted gains in both volcanology and seismology. Since 1980, scientists have learned to better predict volcanic eruptions by studying earthquake activity, including the “harmonic tremors” that indicate movement of molten earth.

Other volcanic mysteries are also better understood, Crandell said. These include the devastating sideways force of the May, 1980, eruption, the fast-moving and deadly mixtures of matter and gas known as pyroclastic flows and surges, and the mud flows that let loose in minutes after vibrations turn snowfields into walls of water.

Mullineaux and Crandell retired in the mid-1980s, but both remain active in research on Mt. St. Helens.

“I can’t leave it alone,” Crandell said.