Mount Redoubt still hadn't blown its stack as of Sunday evening, but some awesome stuff was happening high atop the restless volcano.
Scientists at the Alaska Volcano Observatory in Anchorage showed stunning pictures from a Saturday flyover to demonstrate the immense forces at work within Redoubt, located 106 miles southwest of Anchorage.
Two holes -- one more than the length of a football field across -- have formed in Drift Glacier below the summit. Each of the holes, known as fumaroles, is blowing steam and volcanic gas 2,000 feet into the air.
A vast sunken area known as a "collapse feature" also has appeared in recent hours. And a thin mudflow is streaming down the 10,197-foot mountain.
It takes immense heat welling up within the volcano to make the giant holes and other features in so brief a time, volcanologist Peter Cervelli said.
Redoubt could explode at any time -- or take its sweet time and keep us in suspense for days or weeks, he said. It also could simmer down and never erupt, though Cervelli believes the chances of that are lower.
If it does blow, Anchorage and the Kenai Peninsula could be showered with ash.
But Cervelli said Anchorage residents need not be overly fearful as ash fall here is likely to be "relatively modest," based on Redoubt's 1989-90 eruption and the geologic record.
"We're not going to be buried in feet of ash, I can assure you of that," Cervelli said.
Volcanic ash is a big worry for aircraft as the particulates can damage engines.
On Sunday, military officials planned to relocate some key aircraft from Elmendorf Air Force Base to McChord Air Force Base near Tacoma, Wash.
The aircraft included five C-17 Globemaster III cargo planes along with about 130 operations and maintenance people, the Air Force said.
"We are taking this precaution to ensure these high-demand assets are available to U.S. Transportation Command when needed," said Col. Richard Walberg.
The huge, four-engine C-17 Globemaster III is used to deploy troops and all types of cargo.
The Air Force said it also has contingency plans to relocate other types of aircraft if necessary due to Redoubt's threat.
A team of 18 volcanologists is keeping a round-the-clock watch on the mountain at the U.S. Geological Survey's volcano observatory in Anchorage, Cervelli said. He confessed they might also keep one eye on Sunday's Super Bowl football game too.
A similar-sized team is on watch at the University of Alaska Fairbanks Geophysical Institute, and more help might be brought up from the Cascades Volcano Observatory in Vancouver, Wash.
On Saturday, scientists took an airplane over Redoubt to snap pictures and to sniff for emissions of gases including sulfur dioxide, carbon dioxide and hydrogen sulfide.
The gases can indicate the existence of shallow magma -- molten rock -- moving up in the volcano, and preliminary analysis indicates these gas emissions are up somewhat, Cervelli said.
Ultimately, the magma can find a crack through which to escape, causing an explosion and towering plume of ash, he said.
The volcanologists also are measuring for seismic activity -- earthquakes -- coming from Redoubt. They detected a sizeable quake at 5:37 a.m. Sunday with characteristics suggesting the movement of underground fluids.
People periodically call the volcano observatory thinking they've seen the eruption start, Cervelli said. Whenever it does blow, he said, it won't be subtle. And seismic activity might provide only an hour or two of warning. Or none at all.
"We don't know exactly when it's going to erupt, but when it does, we're going know it," he said.
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