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Mount St. Helens came back to life a decade ago

Volcano's last eruption, while less destructive, drew lots of attention

By , Columbian Transportation & Environment Reporter
Published:
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The lead-up to Mount St. Helens' last eruption drew widespread media attention in September 2004. Television trucks were a fixture at Johnston Ridge Observatory.
The lead-up to Mount St. Helens' last eruption drew widespread media attention in September 2004. Television trucks were a fixture at Johnston Ridge Observatory. Photo Gallery

Key events in the 2004-08 eruption of Mount St. Helens:

o Sept. 23, 2004: A swarm of tiny, shallow earthquakes beneath the 1980-86 lava dome begins at 2 a.m. The swarm increases in intensity, then declines within two days.

o Sept. 25: Larger, low-frequency earthquakes begin to occur, signaling the possibility of an eruption.

o Sept. 26: Cracks appear in glacier ice, indicating the intrusion of rising magma. The Cascades Volcano Observatory issues a “notice of volcanic unrest” and raises the aviation color code to yellow.

o Sept. 29-30: Seismicity accelerates; the CVO issues a Level 2 volcano advisory and raises the aviation color code to orange because of concern that explosions could affect air traffic. Scientists peg the chance of an eruption at 70 percent.

o Oct. 1: At 11:57 a.m., a 20-minute explosion sends an ash and vapor cloud about 2 kilometers into the air. The eruption is clearly visible from Vancouver and Portland. A tiny bit of ash falls in the metro area.

o Oct. 2: After continued seismic activity indicates magma movement or pressurization, scientists issue a Level 3 volcano alert and raise the aviation color code to red. Johnston Ridge Observatory and state Highway 504 are evacuated near the mountain.

Key events in the 2004-08 eruption of Mount St. Helens:

o Sept. 23, 2004: A swarm of tiny, shallow earthquakes beneath the 1980-86 lava dome begins at 2 a.m. The swarm increases in intensity, then declines within two days.

o Sept. 25: Larger, low-frequency earthquakes begin to occur, signaling the possibility of an eruption.

o Sept. 26: Cracks appear in glacier ice, indicating the intrusion of rising magma. The Cascades Volcano Observatory issues a "notice of volcanic unrest" and raises the aviation color code to yellow.

o Sept. 29-30: Seismicity accelerates; the CVO issues a Level 2 volcano advisory and raises the aviation color code to orange because of concern that explosions could affect air traffic. Scientists peg the chance of an eruption at 70 percent.

o Oct. 1: At 11:57 a.m., a 20-minute explosion sends an ash and vapor cloud about 2 kilometers into the air. The eruption is clearly visible from Vancouver and Portland. A tiny bit of ash falls in the metro area.

o Oct. 2: After continued seismic activity indicates magma movement or pressurization, scientists issue a Level 3 volcano alert and raise the aviation color code to red. Johnston Ridge Observatory and state Highway 504 are evacuated near the mountain.

o Oct. 6: After days of small explosions and steam and ash emissions, seismicity decreases. The volcano alert is lowered to Level 2, and the aviation color code is lowered to orange. But activity continues in the coming months as a rock "spine" grows inside the crater.

o Jan. 16, 2005: The first of two significant explosions occurs without giving off any warning signs to volcanologists.

o March 8: The second of two significant explosions occurs, again with little warning. A large ash cloud rises from the crater, and ash dustings are reported as far as 90 miles from the volcano.

o 2005 to 2008: Continued activity releases semi-solid lava and forms a dome-like mass in the crater. Gas emissions continue.

o January 2008: The eruption ends. The new lava dome measures 124 million cubic yards.

Sources: U.S. Geological Survey, Columbian archives

o Oct. 6: After days of small explosions and steam and ash emissions, seismicity decreases. The volcano alert is lowered to Level 2, and the aviation color code is lowered to orange. But activity continues in the coming months as a rock “spine” grows inside the crater.

o Jan. 16, 2005: The first of two significant explosions occurs without giving off any warning signs to volcanologists.

o March 8: The second of two significant explosions occurs, again with little warning. A large ash cloud rises from the crater, and ash dustings are reported as far as 90 miles from the volcano.

o 2005 to 2008: Continued activity releases semi-solid lava and forms a dome-like mass in the crater. Gas emissions continue.

o January 2008: The eruption ends. The new lava dome measures 124 million cubic yards.

Sources: U.S. Geological Survey, Columbian archives

On a late-September weekend in 2004, Seth Moran received a phone call while mowing his lawn. It was about Mount St. Helens, which only days earlier had caught scientists’ attention with a swarm of shallow earthquakes.

On the phone was Steve Malone, a seismologist with the University of Washington. The nature of the activity at the mountain had changed, he said. It looked like Skamania County’s notorious volcano could be reawakening.

Moran, a U.S. Geological Survey seismologist, went into his office at the Cascades Volcano Observatory in Vancouver.

“And that was the last time I think I was home for about three weeks,” Moran said.

That’s what it felt like, anyway. Ten years ago this week, Moran and other CVO scientists worked 12- to 16-hour days keeping constant watch on Mount St. Helens in the lead-up to its last eruption. The office went to around-the-clock monitoring. Officials held daily press conferences amid an overwhelming media crush.

“It was real-time science for a lot of us,” Moran said. “That’s not typically the way science works, and scientists work.”

On Oct. 1, 2004 — barely a week after Moran was mowing his lawn — a steam and ash explosion in the crater capped days of suspense.

But that was just the beginning. The eruption would continue for more than three years, building a new lava dome measuring 124 million cubic yards in volume, enough to fill millions of dump trucks. Mount St. Helens returned to relative slumber in early 2008.

The 2004-2008 eruption was notable for its lack of explosive events, according to the U.S. Geological Survey. The only two significant explosions occurred in January and March of 2005. Both were a far cry from the catastrophic blast that decapitated the peak on May 18, 1980.

Even in the uncertain days of September 2004, scientists knew they probably weren’t in for a repeat of 1980, said Cynthia Gardner, who was acting scientist in charge at the time. But staff held daily meetings to discuss all possible scenarios, from the most likely to the outliers, she said.

Scientists’ first priority during a volcanic event is public safety, Moran said. In addition to the media, CVO was in regular contact with the U.S. Forest Service, the Federal Aviation Administration, emergency management officials and others, he said. But it’s a balancing act to manage alerts and keep people informed while trying not to sound the alarm too soon, he said.

“Volcanoes don’t always play along with the script that you think they’re going to follow,” Moran said.

Gardner described a “hyperactivity” that fueled her and other scientists during the eruption and the days leading up to it. The office scrambled to absorb and interpret a torrent of information coming from the field and other data. Many staff members wouldn’t have gone home even if they could, she said.

“It’s all of our passion,” Gardner said. “It’s stressful, but it’s exhilarating.”

Gardner later became CVO’s permanent scientist in charge, and remained in that position through the end of the eruption in 2008. Mount St. Helens never left her mind during that time, she said.

“You’re just thinking all the time,” said Gardner a geologist who still works at CVO. “You’re just spending every waking moment assessing what you’re seeing, what you’re saying.”

‘Will erupt again’

More than six years after Mount St. Helens quieted, scientists haven’t stopped their efforts to better understand the volcano. Researchers this year began an ambitious project that aims to map the vast plumbing system that feeds magma to the mountain. Imaging Magma Under St. Helens involves dozens of seismic sensors that scientists hope will improve their ability to forecast future eruptions.

Mount St. Helens is only one of several volcanoes CVO monitors in the Northwest. Mount Hood, Mount Adams and others all have the potential to reawaken someday, according to the U.S. Geological Survey.

The 2004-2008 eruption won’t be the last time Mount St. Helens acts up. Scientists confirmed earlier this year that magma underneath the volcano is repressurizing, quietly recharging for the next eruption.

Though there are currently no signs of an impending eruption, “we’re all, I think, of the mind that St. Helens will erupt again,” Gardner said, “sooner rather than later.”

Columbian Transportation & Environment Reporter
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