Mt. St. Helens Spews More Steam

Mount St. Helens shot off a new column of steam Sunday that rose out of the crater of the snow-dusted volcano.

A billow of dark steam rose at dawn from an area of the crater where a large upwelling of rock has been growing rapidly. The plume rose several hundred feet above the 8,364-foot volcano, and light wind slowly blew it toward the south and southeast.

Scientists did not immediately determine whether the steam cloud contained any volcanic ash, said an information officer at the joint information center in Vancouver, Washington, about 50 miles south of the mountain.

The steam emission followed an increase in earthquake activity over the previous two days, with quakes of magnitude 2.4 occurring every two minutes until Sunday, when the vibrations were more frequent but weakened to magnitude 1 or less.

"What has been peculiar about these earthquakes is that there seems to be a disproportionate number of them that are uniform in size," said seismologist Tony Qamar at the University of Washington's seismic lab in Seattle.

It indicates that pressure in the system is very uniform, which may suggest magma is constantly moving upward, he said. "The pressure will build up, the rock will break, and then you'll get an earthquake," Qamar said.

"Exactly where the magma is, since we don't have visuals, we just can't say," said Jeff Wynn, the U.S. Geological Survey's chief scientist for volcano hazards at Vancouver.

Seismic activity on Saturday was equal to or higher than levels during the Oct. 5 eruption that sent a thick gray cloud thousands of feet into the air and dusted some areas northeast of the volcano with gritty, abrasive ash.

Geologists do not anticipate anything similar to the May 18, 1980, blast that killed 57 people, blew 1,300 feet off the top of the peak and covered much of the inland Pacific Northwest with ash.

A bulge on the south side of the dome-shaped formation of rock in the crater had risen to at least 330 feet since Sept. 30, said USGS geologist John Pallister.

"The blister is a rather remarkable event," he said.

Since Sept. 23, thousands of small earthquakes have shaken the peak in the Cascade Range. The volcano vented clouds of steam carrying small amounts of old volcanic ash each day from Oct. 1 through Oct. 5. Thousands of people were evacuated from areas around the mountain on Oct. 2.