06:15 PM PDT on Saturday, October 9, 2004

By ABE ESTIMADA, kgw.com Staff

MOUNT ST. HELENS, Wash. – -- Earthquake activity has increased at Mount St. Helens and a bulge on the south side of the lava dome has risen to at least 300 feet since scientists first spotted it on September 30th, officials said.

AP

Surrounded by clouds, steam is seen venting out of three locations inside the crater of Mount St. Helens on Thursday at Mount St. Helens National Monument, Wash.

The bulge, also described as a new lava dome, is now almost as tall as the dome's 1,000-foot summit, according to Geologist John Pallister. He described the blister growing inside the crater as a remarkable event that suggests magma is somewhere at shallow depths less than a mile below the surface.

It took Mother Nature six years to build the old lava dome.

Pallister said scientists will continue monitoring the bulge to see how the uplift relates to the seismic activity.

"Seismic activity leveled off overnight after rising gradually for most of yesterday, with earthquakes up to magnitude 2.4 presently occurring at a rate of about one every two minutes," Tom Knappenberger, a spokesman for the Mount St. Helens Joint Information Center, said Saturday.

Despite the swelling and the increase in earthquake activity, scientists said there was no reason to raise the alert level from "volcanic advisory" around the 8,364-foot volcano. Geologists last week lowered the alert to Level Two, the highest before an eruption.

Scientists believe an eruption is still possible. There may be little time to raise the alert level before a possible hazardous eruption occurs, according to U.S. Geological Survey scientists who are asking nearby residents to collect ash and turn it in for analysis.

In the event of a powerful eruption, lava could spill out well beyond the crater, scientists said during a news briefing on Saturday afternoon.

The new outgrowth spurred debate on Friday among geologists about how close the magma is to the surface and how strong an eruption could be.

While the new lava dome is rising from the crater, it’s pushing the old lava dome about four centimeters to the north. The old lava dome at the center of the crater has been forming since the May 18, 1980 eruption.

Scientists agree that magma is pushing the new lava dome upward. Gas flights inside the crater have detected carbon dioxide and sulfur dioxide, which are gases associated with magma.

Magma is heating rocks, which are in turn bringing ground water to boil. That's producing the continual steam venting coming from the volcano.

Scientists, however, do not know how much magma is below or when it will reach the surface.

AP

Alan Douglas, with KING television out of Seattle, braces against blowing rain as he trains his camera towards Mount St. Helens, which is covered in dense clouds in the distance on Friday.

One theory is that new magma has pushed up to within two-thirds of a mile beneath the lava dome. From there, the magma is welling up and exerting pressure on the rocks above, causing the new lava dome to build, said Pallister.

The other hypothesis that scientists have developed is that the magma is just below the lava dome, ready to break to the surface. That could be the cause of the small, shallow quakes that their instruments have picked up for the last several days.

How close the magma is to the surface may determine how explosive an eruption could be. If molten rock is indeed just below the lava dome, by the time it reaches the surface, it will likely have “de-gassed” and won’t pack as big a punch, scientists said.

But if the magma is trapped two-thirds of a mile below, it’s getting time to build pressure, raising the chances of a more explosive eruption, Pallister said.

"We maintain a range of possibities from most likely dome growth, smaller eruptions, smaller explosions to larger explosions if the magma gets to the surface very rapidly," Pallister said.

With the onset of poor weather, scientists are relying on their equipment on the lava dome and throughout the flanks of the lava dome to tell them what is happening on Mount St. Helens.

Scientists have been closely monitoring the volcano since Sept. 23, when swarms of earthquakes were detected. It was the most activity on the volcano since before the 1980 eruption.

Beginning Friday and ending Tuesday, the mountain saw at least six, major steam explosions that have been visible all the way to the Portland metro area. Throughout last weekend and into Tuesday, the alert was raised to Level Three, signaling an imminent eruption, after scientists detected tremors that came from the movement of magma below the mountain.

The U.S. Forest Service reiterated on Saturday that closures around the volcano — including the Johnston Ridge observatory five miles north of the crater — would remain in effect until authorities determine the area is safe.

AP

Kyra Farthing, 5, of Portland, holds her bunny as she peers in the direction of cloud covered Mount St. Helens.

The Coldwater Ridge Visitors Center, 8 1/2 miles north of the mountain, is the closest vantage point where visitors are allowed. Johnston Ridge is usually closed for the winter by the end of October.

Though the mountain is relatively quiet compared to Tuesday’s steam and ash blast, scientists and emergency management personnel warn that conditions can change at any moment.

“The best thing is to be cautious, expect a range of events,” said Jake Lowenstern, a USGS geologist.

(The Associated Press also contributed to this article.)