ANCHORAGE, Alaska — 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 around 8:30 a.m. shot an ash cloud about 30,000 feet in the air, and a second eruption about an hour later sent ash 65,000 feet high _ the highest cloud since the eruptions began. Five to 10 smaller eruptions followed, with none of their plumes surpassing 20,000 feet.
The largest eruption caused a mud flow into the Drift River near the base of the volcano.
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.
The National Weather Service said prevailing winds were 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.
The weather service said a trace of ash was reported south of Kenai and at its airport, but it wasn't expecting any significant accumulation from Thursday's eruptions.
Ash dropped Thursday afternoon 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 and turned the snow into what looked like a carpet covered with gray dots.
"It is falling pretty fast," she said.
Anchorage spokeswoman Jenny Evans said the state's largest city, roughly 100 miles northeast of the volcano, could see trace amounts of ash.
Alaska Airlines canceled all flights to and from Anchorage until sunrise Friday, and all planes at Elmendorf Air Force Base in Anchorage were either placed in shelters or moved to other bases. Ash poses a significant threat to aircraft engines.
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.
Prejean said it was not known if the mud flow produced Thursday reached the oil storage facility.
Eleven employees were evacuated from the terminal Monday. Lana Johnson, a consultant for Cook Inlet Pipeline Co., said two crews reached the terminal by helicopter on Thursday but were evacuated when the volcano erupted. Previous flights had indicated that the oil storage tanks were not damaged and surrounding berms and dikes to contain any spilled oil were also OK.
Johnson said there was monitoring equipment at the terminal that could be read remotely, and the system indicated the tanks were holding the oil.
Sara Francis, spokeswoman for the U.S. Coast Guard, said "the safest place for that oil to be right now is in those tanks."
Since the first series of eruptions 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.
Scarpitta, the B&B owner, said she's expecting the arrival of visitors "from another disaster area" _ along North Dakota's Red River, where a historic crest was expected Saturday and thousands of sandbaggers were trying to prevent widespread flooding. Scarpitta said a family was 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.