Scientists drop alert level at Mount St. Helens

By Hal Bernton and Ian Ith
Seattle Times staff reporters

BRUCE ELY / THE OREGONIAN Mount St. Helens exhales another cloud of steam and ash yesterday, its third explosion in less than a week. This aerial photo was taken over Mount St. Helens National Monument.

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But how long that lull will last is anybody's guess.

The alert level at the volcano remained at 2 this afternoon, which means scientists don't believe an eruption that would endanger life or property is imminent.

The Johnston Ridge Observatory five miles from the crater is still closed.

Lots of earthquakes still keep the seismometers on the mountain bouncing, but the temblors are not noticeable to anything but the sensitive equipment. They are amounting to no more than 1 on the Richter scale, as compared to the 2 and 3 magnitude quakes that shook during the volcano's spectacular ash and steam blow-offs earlier.

The ash, which reached communities in eastern Lewis County in small doses yesterday, has not shown signs of containing fresh magma, which suggests that the new magma that is pushing bulges in the volcano's lava dome is still 100 meters or a few hundred meters below the surface.

Today scientists noticed that a global-positioning device on the north side of the crater has moved 2 centimeters, which means the volcanic processes below are still underway.

But the decrease in the earthquakes is telling scientists that the magma has probably stopped rising for the time being.

It's normal for volcanoes to cough to life, then pause for a time before coughing to life again, said Tom Pierson, a U.S. Geological Survey geologist. But scientists can't predict when the lull will end.

It could be only a matter of a day or so, because the quakes are slightly more intense today than overnight. But very often volcanoes will pause for eight or ten weeks or more, he said.

"We really are expecting this to turn around and follow with some kind of activity," Pierson said. "It's unlikely it will go back to sleep."

Today geologists managed to get a helicopter out to view the results of some minor lahars, or mudflows, that washed down the volcano for a short distance after last night's heavy rain.

	TROY WAYRYNEN / THE COLUMBIAN Mount St. Helens during yesterday's explosion, as seen looking north with Mount Rainier in the background.

But there was no sign of damage. Pierson said even in scientists' worst-case scenarios, the biggest mudflow would be about 50 million cubic meters of water and ash and debris.

That sounds like a lot. But scientists calculate that a sediment dam built on the Toutle river 23 miles downstream from the volcano would be sufficient to hold back that large of a flow and protect downriver communities such as Toutle and Castle Rock.

The government has dropped the volcano alert level from 3, the highest level, to 2, meaning simply that an alert still exists but a strong eruption is not expected immediately.

Johnston Ridge Observatory, at five miles away and the closest tourist spot to the crater, remained closed today because scientists believe the mountain could potentially spring to life so quickly. Trails and campgrounds in the near vicinity remain closed, too.

Skamania County Undersheriff Dave Cox said this morning that deputies yesterday rounded up several people who had hiked into closed areas " trying get a better view of the mountain."

He said the closures are meant to protect people, and "if we had to go in and do a search-and-rescue, it puts a lot of search-and-rescue people at risk."

Scientists say the mountain is likely in a phase of magma buildup that could result in small-scale eruptions of steam and ash for weeks or months, or possibly even years.

But the scientists have said since last month that they don't expect any eruption that would come close to rivaling the catastrophic blasts of May 1980.

The mountain is much different now that it was then, they say, and scientific measuring equipment is more sophisticated and more abundant on Mount St. Helens than it was 24 years ago.

The latest explosion was at 9:03 a.m. yesterday, with a few white puffs from the crater morphing into larger, darker clouds that rose some 13,000 feet. The clouds drifted to the northeast, and the ash that dropped from them looked from a distance like rain falling from a thunderhead.

A light dusting of ash was reported in Randle and Packwood in eastern Lewis County, 40 miles or so from the volcano. State emergency-management officials said there was no reason for concern, and that the ash didn't affect daily life in the small timber towns.

"It's a light coating, enough so when you drive it blows up off the highway," said Jeanette Blankenship at the Woodland Motel, 10 miles east of Randle. "But this is nothing like 1980."

Aviation wasn't significantly affected by the emissions yesterday. But the Federal Aviation Administration expanded a no-fly zone that had been limited to the area directly above the volcano. It now includes the area within a five-mile radius of the mountain.

That was primarily to make sure the skies are clear around the volcano in case emergency flights need to get in, said Julie Stewart of the U.S. Department of Agriculture, which manages the land around St. Helens. Media and scientific flights still are permitted, she said.

Yesterday's explosion helped in a rapid resculpting of the inner crater, which as of yesterday had three new vent holes. A section of the crater floor about the size of a hundred football fields has lifted up by an estimated 150 feet.

The deformed area has a new nickname: "The Loaf."

Yesterday's explosion, which lasted about an hour, unfolded right on cue for the encampment of journalists now spread across the parking lot at this viewpoint across Highway 504. Many turned immediately to U.S. Geological Survey scientist Jon Major for analysis.

Major found the initial plume "pretty lazy. It's not building up too rapidly."

The eruption did manage at least temporarily to reduce pressure in the crater.

The volcano is likely to put on a lot more such shows in the future. Scientists note that the mountain went through six years of activity between 1980 and 1986.

"People are going to have to get used to seeing vulcanism," said Jake Lowenstern, a U.S. Geological Survey vulcanologist.

Though it was much punier than the May 18, 1980, blast that killed 57 people, yesterday's explosion was the largest and longest since the mountain began to stir last month. Scientists say yesterday's release resulted from water vaporized by heat from magma deep underground, which may reach temperatures of more than 1,000 degrees Celsius.

U.S. Geological Survey scientists say there is an 80 percent chance the fresh magma eventually will work its way to the surface.

They are unsure whether the gas it contains eventually will trigger a substantial eruption or simply ooze out more quietly. They also are unsure of the magma's depth or quantity. But the increasing deformities of "The Loaf," which includes parts of a crater glacier and the edge of a 920-foot-high lava dome, indicate that the pool of magma is expanding and exerting considerable pressure.

As of yesterday, three Global Positioning System (GPS) monitoring instruments had been placed in the crater. The deployment was a tricky maneuver: A helicopter hovered low above the crater, then lowered the delicate equipment on a cable.

The GPS equipment will become even more important if cloud cover prevents visual observation of the uplift, the scientists said.

Yesterday afternoon, the early-autumn sunshine faded, but the mountain was still visible, its shoulders streaked with fresh gray ash. Dust swirled in the crater. But rain clouds appeared to be drifting up the Toutle River Valley.

That would be bad news for news people who have been fortunate to have mostly clear views of the volcano.

A pair of artists from Southern California said they were ready to put up with some rain. Yesterday, as soon as they had set up canvases to paint the mountain, they instantly became darlings of the news people, who were looking for something to shoot between the volcano clouds.

One of the artists was a shaggy-haired man who calls himself "O." He paints with gallon buckets of acrylic paint that he splashes on a 4- by-5-foot canvas with the aid of paintbrushes lashed to walking sticks. Since arriving late Saturday, he had finished more than a dozen paintings of the mountain and promised more.

"This is a birthing process, the birth of the Earth, and that's my highest truth," he said.

Hal Bernton: 206-464-2581 or hbernton@seattletimes.com; Ian Ith: 206-464-2109 or iith@seattletimes.com

Copyright © 2004 The Seattle Times Company

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