ANCHORAGE - Alaska's Mount Redoubt erupted several times Thursday, spewing a more than 12-mile-high cloud that could drop ash on Anchorage for the first time since the volcano began erupting Sunday night.
The Alaska Volcano Observatory said the first eruption about 8:30 a.m. shot an ash cloud about 30,000 feet in the air, and the second eruption about an hour later sent ash 65,000 feet high - the highest cloud since the eruptions began. The larger eruption caused a mud flow into the Drift River near the base of the volcano.
Officials said there were five to 10 smaller eruptions later, but none of the plumes went above 20,000 feet.
Before Thursday's eruptions the volcano had been relatively quiet for more than a day.
"We can have these large explosions pretty much any time," said Stephanie Prejean, an observatory seismologist. "We don't know how long this will continue."
When Redoubt last erupted 20 years ago, it went on for four months.
According to the National Weather Service, prevailing winds are expected to carry ash from the larger eruption east across Cook Inlet toward some of Alaska's larger communities. An ash fall advisory for the western Kenai Peninsula covers the towns of Kenai, Soldotna and Cooper Landing.
Anchorage spokeswoman Jenny Evans said the state's largest city, roughly 100 miles northeast of the volcano, could see trace amounts of ash.
The smaller cloud Thursday afternoon dropped a light amount of ash on Homer, a tourist and fishing town at the southern tip of the Kenai Peninsula.
Juxia Scarpitta, owner of Halcyon Heights Bed and Breakfast in Homer, said the ash had obliterated her view of the bay. It was turning the snow into what looked like a carpet covered with gray dots.
"It is falling pretty fast," she said. "Right now you see snowflakes, falling all over. I think they are ash."
The National Weather Service says a trace of ash was reported south of Kenai and at the city airport, but wasn't expecting any significant accumulation from Thursday's eruptions.
Ash poses a significant threat to aircraft engines, and a small carrier, Era Aviation, canceled four flights as of midday. Alaska Airlines canceled all flights to and from Anchorage until sunrise Friday.
Elmendorf Air Force Base in Anchorage also moved six planes north to Eielson Air Force, near Fairbanks, and two to McChord Air Force Base near Tacoma, Wash., as a precaution. All other planes at Elmendorf have been placed in shelters.
The National Weather Service also issued a flash flood warning for the Drift River, near the volcano. Eruptions can cause snow and ice to melt on the mountain, resulting in flooding along the river that drains from the mountain.
Research geologists with the U.S. Geological Survey have said a lot of snow and ice remains on the mountain, increasing the danger from mud flows that already have downed hundreds of trees and carved a huge gouge out of a glacier.
The mud flows also have littered the airport at the Drift River Terminal, a Chevron-operated facility that has been shut down but still has 6.2 million gallons of crude stored in two tanks. Until the airport runway is cleared, it is unusable.
Eleven employees were evacuated from the terminal Monday. An attempt to reach the terminal by helicopter on Wednesday was unsuccessful, but previous flights indicated that the oil storage tanks were not damaged and surrounding berms and dikes to contain any spilled oil were also OK.
Prejean said it was not known if the mud flow produced Thursday reached the oil storage facility.
Two crews were delivered by helicopter to the terminal site Thursday morning but were evacuated quickly when the volcano erupted, said Lana Johnson, a consultant for Cook Inlet Pipeline Co., partially owned by Chevron.
The crews included two engineers who were assessing the condition of the facility. The company hopes to get the two engineers back to the site as soon as possible.
Johnson said there was a monitoring system on the tanks that could be read remotely and would show if there was a catastrophic failure. The system indicated the tanks were holding the expected amount of oil.
If the volcano quiets down and the alert level is downgraded, Cook Inlet Pipeline Co. would like to get the oil storage terminal up and running, Johnson said.
"The plan is to resume operations and then at some point when it is appropriate have a tanker offload," she said.
The condition of the terminal's loading site was being evaluated to prepare for the arrival of a tanker in early April, said Sara Francis, spokeswoman for the U.S. Coast Guard.
"The safest place for that oil to be right now is in those tanks," Francis said.
The Coast Guard has the final say on whether the terminal can resume operations.
Conservation group Cook Inletkeeper has been pushing to have the oil removed from the tanks. The organization says if the tanks are damaged by the volcano and fail, it would be disastrous for Cook Inlet fisheries.
"Anybody that looks at this in a rational way understands this is an inherently unsafe situation," said executive director Bob Shavelson.
Since the first series of eruption Sunday night and early Monday morning, the volcano has had several smaller bursts with most ash falling on sparsely populated areas northwest of Anchorage. Some people in more populated areas were nervous about getting a dusting from Thursday's eruptions.
At the Homer B&B, Scarpitta said she's expecting the arrival of visitors "from another disaster area" - along North Dakota's Red River, where a historic crest is expected Saturday and thousands of sandbaggers are trying to prevent widespread flooding. Scarpitta said the family is coming so one of them can celebrate his birthday in Alaska.
"He is still coming right now. I advised him to get trip insurance," she said.
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