(AP) -- 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 a second eruption about an hour later sent ash 65,000 feet high - the highest cloud since the eruptions began. Several 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.
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.
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.
Minor amounts of ash were expected to fall on Homer, a tourist and fishing town at the southern tip of the Kenai Peninsula.
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.
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.
"Right now there is nothing really we can do but shut the doors, keep ourselves closed up," said Juxia Scarpitta, owner of Halcyon Heights Bed and Breakfast in Homer.
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.
©2009 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.
Explore further: Deciphering clues to prehistoric climate changes locked in cave deposits