Temperatures soar in Mount St. Helens' crater

By RUKMINI CALLIMACHI
The Associated Press

DON RYAN / AP A steam plume colored by the sun rises above the crater of Mount St. Helens yesterday. "The steam plume is essentially a constant feature that will be there for days to come," geologist Willie Scott said.

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Scientists said an area on the south side of the old dome, where a large uplift of rock has been growing, appears perforated as if magma has been hammering at the surface.

"What's happened in the last day is the magma is not just pushing up but pushing out. We no longer have just isolated vents. Instead the whole area is pushing up, the gas is the fuse, just oozing out," John Pallister, a U.S. Geological Survey geologist, said at a news conference yesterday afternoon.

He said scientists have not actually seen the magma, which they think is less than half a mile below the surface.

Fast-moving magma would cause greater concern because explosive gases wouldn't have time to dissipate. A team in Denver is evaluating air photos, comparing pictures of the changing lava dome to gauge how fast the magma is rising.

"Rapid ascent is very dangerous, whereas if it rises slowly the magma has a chance to degas and then it would just ease its way out," Pallister said.

The alert level remains at "volcano advisory," but scientists have said an eruption could occur with very little warning.

Pallister said the most likely scenario remains an explosion with a few inches of ash spreading out within 10 miles of the crater. Such an eruption could happen in days, weeks or months — or not at all, he said. Scientists think the chance of a large eruption like the one on May 18, 1980, which killed 57 people, is slim.

Willie Scott, another U.S. Geological Survey geologist, said earlier yesterday that temperatures in some spots of the dome could be as high as 400 to 570 degrees Fahrenheit.

Readings taken during a Sunday flight over the volcano went off the charts, said Jeff Wynn, chief scientist for volcano hazards at the USGS's Cascades Volcano Observatory.

Scientists couldn't get precise temperatures for the hottest parts of the lava dome — on the south side — because the instruments weren't calibrated high enough, Wynn said.
 
"They didn't expect it to get that hot," he said.

The mountain gave off more steam yesterday, with a cloud drifting up hundreds of feet from the rim of the crater as the sun rose, much like Sunday's emission.

"The steam plume is essentially a constant feature that will be there for days to come," Scott said.

In addition to spotting rising temperatures, scientists have detected an increase in emissions of carbon dioxide and sulfur dioxide, another sign that magma is rising.

During a flight last Thursday, instruments measured the mountain emitting about 2,000 tons a day of carbon dioxide — up from 100 tons a day earlier this month — and roughly 100 tons of sulfur dioxide, Scott said.

While significant, both of those readings are much lower than ones taken during some of the early 1980 eruptions, Scott said.