After quakes, steam eruption at Mount St. Helens

By David Ammons
The Associated Press

STEVE RINGMAN / THE SEATTLE TIMES With spectators celebrating at the Johnston Ridge Observatory, Mount St. Helens erupts with steam and ash.

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The eruption was the first in 18 years at the volcano, which exploded with devastating force and killed 57 people on May 18, 1980.

"It was such a thrill!" said Faye Ray, a retired school teacher who watched from an observatory near the mountain. "I just felt we would see something today and we did."

At about noon PDT, there was a small explosion, followed by a steam and ash cloud that poured from the southern edge of a nearly 1,000-foot-tall lava dome in the volcano's crater. A large section of a glacier there had fractured and risen as much as 11 yards in the 24 hours before the eruption, scientists said.

After about 20 minutes, the mountain calmed and the plume quickly dissipated, revealing a 100-foot-wide crater in the 600-foot-deep glacier. Apparently no magma reached the surface.

Small earthquakes had been occurring continuously in the crater since Sept. 23. They grew steadily stronger, finally reaching a magnitude of 3.3 yesterday and today, but the earthquakes quit after the eruption, said Jeff Wynn, the chief scientist for volcano hazards at the Cascade Volcano Observatory of the USGS.

He called the eruption a "throat-clearing."

"It's dead — bone-still right now," he said. "There's nothing happening at this stage, so this may have been a single event. But the history of the volcano suggests it could be an opening salvo and we'll see more events like this."

USGS seismologist Bob Norris said magma could be moving underground and he would not be surprised to see more explosions in the next days or weeks. Tom Pierson, a USGS geologist, added, "The monitoring will definitely continue on a very intense scale until we can determine that the thing has really gone back to sleep."

Mike Fergus, a spokesman with the Federal Aviation Administration in Seattle, said the plume had reached 16,000 feet in altitude, and his agency warned pilots to avoid it.

Alaska Airlines canceled six flights scheduled to take off from or land at Portland International Airport in Oregon and diverted three other flights headed for Portland to Seattle-Tacoma International Airport, said spokesman Sam Sperry. But the airline quickly resumed its normal schedule.

The small ash cloud from the eruption drifted south-southwest, and scientists warned that anyone living in that direction might notice a fine film of ash on their cars.

Scientists had not expected anything like the mountain's devastating eruption in 1980, which coated much of the Northwest with ash. On Wednesday, they warned that a small or moderate blast from the southwest Washington mountain could spew ash and rock as far as three miles from the crater at the 8,364-foot peak.

Few people live near the mountain, the centerpiece of the Mount St. Helens National Volcanic Monument in the Gifford Pinchot National Forest about 100 miles south of Seattle. The closest structure is the Johnston Ridge Observatory, about five miles from the crater.

"It wasn't lava-y, so I wasn't scared," said Lorain Weatherby, who was working a snack bar down the road from St. Helens. "It was like a big white cloud."

Copyright © 2004 The Seattle Times Company

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