Dome continues to grow at Mount St. Helens

06:45 PM PDT on Wednesday, October 20, 2004

From KING Staff and Wire Reports

SEATTLE — Scientists got their first good look at Mount St. Helens Wednesday after the clouds cleared up, revealing a snow covered volcano still steaming and the new dome growing slowly but steadily.

Clouds and fog had obscured the crater since before last weekend, but the clearing allowed scientists to calculate and confirm the new dome was growing in size and that new lava was still pushing up to the surface.

Snow fell over much of the mountain Monday, creating an incredible amount of steam at the volcano and increasing the risk of lahar in the nearby areas.

With a break in the clouds, a helicopter dragging a five-gallon bucket flew over the volcano, collecting rock and ash samples from inside the crater. USGS scientists planned to analyze the rock and ash samples for more information about the magma that is rising to the surface.

They also hoped to experiment with use of an unmanned aircraft 5 feet long with an 8-foot wingspan, a drone developed for the military. If the experiment works, drones could be used to provide visual images and gather gas samples during the fall and winter.

“Normally, you can’t see this volcano for six months out of the year because it’s socked in the clouds,” Wynn said. “This is the Pacific Northwest.”

KING

A snow-covered Mount St. Helens continued to emit steam Wednesday.

Small earthquakes have also begun rumbling more frequently beneath Mount St. Helens, and scientists said they’re trying to determine what the change signifies.

Some think it could be significant and others say it’s just more of the same, indicating a slow, steady growth of the lava dome in the volcano’s crater that could continue for a year or longer.

Jeff Wynn, chief scientist for volcano hazards at the U.S. Geological Survey’s Cascades Volcano Observatory in Vancouver, Wash., said Monday the seismic and electronic signals are different from anything scientists have seen since the mountain reawakened 3 ½ weeks ago.

Four days earlier, a seismograph recorded a chain of earthquakes resembling a series of heartbeats, seismic activity rising and falling.

On Monday, a seismograph at the same part of the mountain showed what looked like a chain of pearls — steady, more frequent earthquakes but without the rising and falling.

Steve Malone, director of the Pacific Northwest Seismograph Network at the University of Washington in Seattle, said only a highly skilled observer could detect the slight changes.

“This is really not anything significant,” Malone said.

Geologists have said there is little chance of anything like the sideways explosion that blew 1,300 feet off the top of the peak and killed 57 people on May 18, 1980.

Wynn said the new signals included a steady flurry of small quakes similar to ones recorded in 1984 with an intensity of less than magnitude 1 but more frequent, about every 10 minutes, than they were several days ago.

Thousands of earthquakes — many of them tiny, some exceeding magnitude 3 — have shaken Mount St. Helens since Sept. 23, apparently from magma breaking through rock as it rose toward the surface. Several steam bursts followed, and geologists detected fresh lava at the surface Oct. 12.

The previous round of dome-building lasted six years, beginning in the months after the 1980 eruption.

The Johnston Ridge Observatory, the closest outpost to the crater at five miles to the north, will most likely not reopen this year, said Gifford Pinchot National Forest spokesman Tom Knappenberger said.

Perched at an elevation of 4,200 feet, Johnston Ridge normally closes at the end of October when snow makes it hard to reach.

It was evacuated Oct. 2, when scientists said the rising possibility of an eruption posed a risk to the public, land remained closed after the alert was lowered four days later.

The observatory was named for USGS geologist David Johnston, who was killed on the ridge in the 1980 eruption.

KING 5's Glenn Farley and the Associated Press contributed to this report.