Update: Redoubt volcano is relatively quiet this morning. The volcano emitted an ash plume at 11:26 p.m. Monday that rose to 25,000 feet but then dissipated over Cook Inlet, according to the Alaska Volcano Observatory. The AVO says there are indications a new dome is forming.
Low-level ash and steam boiled out of Mount Redoubt through the day Monday, briefly stalling air traffic in Anchorage, causing continued concern for the precariously placed Drift River oil terminal and leaving scientists wondering what the volcano's next move would be.
The easing of seismic activity followed a weekend of explosive bursts that dusted Anchorage in ash and forced the international airport to close. But while ash fall advisories and violent eruptions were absent Monday, the Alaska Volcano Observatory reported the stratovolcano was still demanding attention, with dark plumes steadily pushing out its summit.
Early in the afternoon, geophysicist Stephanie Prejean said the volcano had switched gears, moving into frequent low-level eruptions in which a "continuous ash plume" is mostly staying below 20,000 feet, with a few clouds reaching as high as 27,000 feet above sea level. Earlier bursts thrust ash and steam more than twice that high.
It wasn't the first time scientists had seen such continuous activity -- both Mount Redoubt the last time it erupted in 1989-1990 and Mount Augustine behaved similarly at times. But whether the steady stream was a precursor to more explosive eruptions or meant the volcano was sputtering out was hard to predict.
"We don't know how this eruption style might continue. It could continue for some time, but this is also a very unstable system, so we could also go back to seeing these large explosions," Prejean said. "As this eruption progresses, however, we also might move into a generally, over the longer-term, less explosive activity as the gaseous magma has opened the system and gotten out of the way. Either of those things could happen."
What ash was billowing out of Redoubt's summit moved slowly to the northeast but fell to earth relatively close to the volcano, and none was expected to reach population centers in the Cook Inlet area.
"We are having a plume -- mostly steam with some ash -- and the plume is going to about 15,000 feet, maybe puffing up to 20," geologist Kate Bull said. "Not a huge amount of ash. We have no indication of ash getting any farther than 20, 30 miles from the volcano."
The volcano's alert level remained at "red" Monday night, but there were no flight restrictions at airports in the region.
Earlier in the day, concern over the continuing ash emissions prompted Alaska Airlines to cancel all its flights into and out of Anchorage, but the lack of immediate danger led the company to reverse course a few hours later and allow flights to resume, with conditions reviewed on an hourly basis, said Paul McElroy, spokesman for the airline.
No other commercial airlines announced plans for major cancellations into or out of Anchorage, although other flights might be halted on an individual basis, said Ted Stevens International Airport operations manager Jim Iagulli.
"It's totally up to the airlines, but they haven't informed us of anything else," he said.
The volcano's erratic behavior was also affecting cargo flights into Anchorage, Iagulli said. While the airport normally receives between 80 and 100 such flights per day, only a handful were expected to arrive Monday.
Since the current series of eruptions began more than a week ago, the volcano has stirred concern over the oil stored at a facility in the Drift River floodplain, which has been pummeled by mudflows pouring down the mountain.
At a news conference Monday, a new unified command set up to deal with hazards at the terminal introduced itself with a sobering dilemma: there is no easy way to deal with the 6 millions gallons of oil stored at the site. Leaving it in place keeps a toxic brew threatened with flooding, while removing it presents hazards of its own.
The command, established over the weekend, is made up of representatives of the terminal's owner, Cook Inlet Pipeline Co., and its two main regulators, the Alaska Department of Environmental Conservation and the U.S. Coast Guard.
Representatives of the three told reporters that the command structure will help them make better and faster decisions about the terminal, which sits in a floodplain about 25 miles downstream from the volcano. So far, a $20 million protective dike built in 1990 has kept floodwaters and volcanic mud out of the facility, but the representatives said a serious threat remains of a calamitous oil spill into the rich marine environment of Cook Inlet.
Gary Folley, the DEC's designated on-scene coordinator, had just driven up from Soldotna when the news conference began and he said he will be representing the state in the command. He said the DEC would like to see the tanks emptied as soon as possible, but recognized that's easy to say, but difficult to accomplish -- even if a tanker becomes available later this week and can dock safely at the facility.
The oil terminal is a key way station in the passage of oil from the offshore production platforms on the west side of Cook Inlet to the Tesoro refinery in Nikiski.
Folley said one problem with draining the tanks is that the pumps at Drift River don't draw oil from the bottom of the tanks, but from about two feet up the side.
"It's not analogous to draining your bathtub," he said.
The tanks are so large that a couple of feet of oil below the pump inlets translates to about a million gallons that can't be removed with the installed equipment, Folley said. And if the tanks are drawn down that far, they risk being too buoyant in the event of a flood and could float off their foundations.
"We don't want to create a situation that is riskier than it is now," Folley said.
Rod Ficken, Cook Inlet Pipeline Co. vice president and the company's representative in the unified command, said water could be used to ballast the tanks, but that creates a new problem: corrosion. Additionally, it might be hard to find a tanker to take the contaminated water-oil mixture to a treatment facility because it would be corrosive to the ship as well, Ficken said.
The 6 million gallons are stored in two tanks at the facility. Five other tanks at Drift River are empty and cleaned, Ficken said. The empty tanks are open; in the event of a flood, they would fill with water and not be buoyant, he said.
Ficken, Folley and the Coast Guard representative at the news conference, Cmdr. Jim Robertson, said the dike remains the single most important factor in keeping the facility safe.
Robertson said oil-spill response equipment has been beefed up in Cook Inlet, and that more could be made available from Prince William Sound.
As for the command structure itself, Folley said the state had not ceded its oversight authority by joining a troika. He said his experience is that a unified command makes better decisions even as it seeks consensus among parties with different interests.
Find James Halpin online at adn.com/contact/jhalpin or call him at 257-4589.