Mount St. Helens' lava dome grows steadily

By Sandi Doughton
Seattle Times staff reporter

DOUG BEGHTEL / THE OREGONIAN Red-hot magma can be seen as new rock is pushed up adding to the new lava dome inside the crater of Mount St Helens yesterday.

E-mail this article Print this article Search archive Most read articles Most e-mailed articles

Other links Photo gallery: Mount St. Helens, then and now Red-hot lava offers spectacular nighttime views of St. Helens Mount St. Helens VolcanoCam Mount St. Helens Seismicity Information Mount St. Helens National Volcanic Monument Mount St. Helens remembered

Red incandescence from the 1,200-degree lava can reflect off clouds and steam, creating a rosy glow in the sky at night, said U.S. Geological Survey (USGS) scientist Tina Neal.

"People may be able to see the glow from many vantage points around the volcano," she said.

A massive slab of hot lava the color of medium roast beef, which first appeared in the crater late Monday or early Tuesday, is expanding steadily, scientists say, though the surrounding curtains of steam make it difficult to get firm measurements.

The slab protrudes from an uplifted area that has risen more than 400 feet over the past two weeks.

On Tuesday, researchers used a helicopter to lower a package of instruments onto the swollen area — nicknamed the Blister — and hope to soon get better data on how rapidly it is expanding. They call the temporary measuring station "Blis," which is both a diminutive and a nod to the fact that the instruments probably won't survive long in the hot, hostile environment.

"Bliss is often known to be short-lived," joked University of Washington seismologist Steve Malone.

	ELAINE THOMPSON / AP Char Morean, of Litchfield Park, Ariz., peers through binoculars at Mount St. Helens about eight miles away at the Coldwater Ridge Visitors Center. A new dome in the crater continues to grow, while steam, ash and gases are still being released.

A seismometer in the package already is sending readings back to Malone's Seattle lab, measuring the ongoing rumble of very tiny earthquakes.

"It's jiggling away," Malone said.

The package also includes a tilt meter, which will help measure expansion of the Blister, and a microphone to pick up the sounds of explosions. A Global Positioning System (GPS) instrument that would have provided another way to measure ground deformation doesn't appear to be working.

Researchers also are awaiting Federal Aviation Administration approval to use an unmanned drone aircraft the size of a large model plane. The drone, which could fly in bad weather that would ground research helicopters, could be equipped with cameras, heat sensors and gas analyzers. It also could fly much closer to steaming vents than wary scientists are willing to go, said USGS volcanologist Willie Scott.

GPS instruments on the flanks of the 8,634-foot peak continue to register no movement, evidence that no large-scale movement of magma is talking place within the volcano's plumbing, Scott said. That includes the mountain's southern flank, despite some local rumors that it was beginning to swell.

"There is absolutely no evidence whatsoever that the south side of the mountain has undergone any deformation or that there are any weaknesses in it," Malone said. That means there's virtually no possibility the mountain's southern side could fail, as the volcano's northern flank did during the cataclysmic 1980 eruption that killed 57 people.

	DOUG BEGHTEL / THE OREGONIAN A steady plume of steam and ash rises from the crater of Mount St. Helens yesterday.

Before that eruption, the northern flank was swelling 5 feet a day, Scott said.

"In 1980, the northern flank was obviously the weak link," he said. "The southern flank of the volcano is like a buttress."

All of the current uplift, swelling and heat seem to be restricted to the volcano's broad crater.

The new lava dome is sprouting near the southern wall of the crater but is still hundreds of yards away and is applying no pressure to the crater wall, Scott added.

Even the worst-case explosive eruption that scientists foresee during this round of volcanic unrest would not be powerful enough to penetrate the crater's southern wall.

Several small towns and lakes line the mountain's southern drains, and they could be at risk if a major eruption ever triggered large mud flows in that direction.

But in this case, "in all of our discussions we never even talked about it because it's so outlandish," Malone said.

Scientists still haven't ruled out the possibility of moderate-sized explosive eruptions, which could fling ash and rock miles around the volcano. Between 1980 and 1986, the volcano erupted several times, ranging from quiet lava flows to steam bursts and ash explosions.

"We are still dealing with a restless volcano," Neal cautioned.

Sandi Doughton: 206-464-2491 or sdoughton@seattletimes.com

Copyright © 2004 The Seattle Times Company

E-mail this article

Print this article

Search archive

More local news headlines...