March 21: Steam rises from the top vent in the summit crater of Alaska's Mount Redoubt.
Alaska's Mount Redoubt volcano erupted six times, sending an ash plume more than 9 miles into the air in the volcano's first emissions in nearly 20 years.
Residents in the state's largest city were spared from falling ash, though fine gray dust fell Monday morning on small communities north of Anchorage.
"It's coming down," Rita Jackson, 56, said Monday morning at a 24-hour grocery store in Willow, about 50 miles north of Anchorage. She slid her fingers across the hood of her car, through a dusting of ash.
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Ash from Alaska's volcanos is like a rock fragment with jagged edges and has been used as an industrial abrasive. It can injure skin, eyes and breathing passages. The young, the elderly and people with respiratory problems are especially susceptible to ash-related health problems. Ash can also cause damage engines in planes, cars and other vehicles.
Alaska Airlines on Monday canceled 19 flights because of the ash. In-state carrier Era Aviation canceled four, and Elmendorf Air Force Base in Anchorage kept 60 planes, including fighter jets, cargo aircraft and a 747 commercial plane, in shelters.
Five of 20 Alaska state senators were scheduled on the morning flight from Anchorage to Juneau, which was canceled. As a result, consideration of legislation, including a resolution accepting federal stimulus funds, was delayed.
The first eruption, in a sparsely populated area across Cook Inlet from the Kenai Peninsula, occurred at 10:38 p.m. Sunday. The sixth happened happened at 7:41 p.m. Monday, according to the Alaska Volcano Observatory.
The wind took the ash cloud away from Anchorage, toward Willow and Talkeetna, near Mount McKinley, North America's largest mountain.
There were reports of a quarter-inch of ash in Trapper Creek and up to a half-inch at a lakeside lodge near Skwentna.
Dave Stricklan, a hydrometeorogical technician with the National Weather Service, expected very fine ash.
"Just kind of a light dusting," he said. He said the significant amount of ash probably dropped immediately, right down the side of the volcano.
"The heavier stuff drops out very quickly, and then the other stuff filters out. There's going to be a very fine amount of it that's going to be suspended in the atmosphere for quite some time," he said. "The finer ash is going to travel farther, and any ash can affect aviation safety."
Jackson said she was taking a sip of coffee when she tasted something funny on her lips — ash. She was experiencing other affects, too.
"My eyes are itching really bad," she said as she hurried to get out of the store and to her car.
Jackson, who unexpectedly got the day off, left the grocery store to secure a motorcycle, snowmachine and vehicles under protective blue tarps at home.
The 10,200-foot Redoubt Volcano, roughly 100 miles southwest of Anchorage, last erupted during a four-month period from 1989-90.
In its last eruption, Redoubt sent ash 150 miles away into the path of a KLM jet and its four engines flamed out. The jet dropped more than 2 miles before the crew was able to restart all engines and land safely. The plane required $80 million in repairs.
The volcano became restless earlier this year. The observatory had warned in late January that an eruption could occur at any time.
Increased earthquake activity over the past 48 hours prompted scientists to raise the alert level for Mount Redoubt on Sunday.
On Sunday morning, 40 to 50 earthquakes were being recorded every hour.
A steam plume rising about 1,000 feet above the mountain peak was observed Saturday.
Three seismometers on the mountain were damaged in the eruption but seven others remained in place, said observatory geophysicist John Power.
The observatory planned a helicopter flight to the mountain Monday afternoon to sample ash, repair equipment and monitor flooding along the Drift River, which flows from a glacier of the same name.
Power said the history of past eruptions of Redoubt indicate the volcano could erupt again in the next few days or weeks.
"It's something we need to stay prepared for," he said.
Le Mont Redoubt le 15 mars 2009
 Le Mont Redoubt, un volcan actif situé à l'ouest de la ville d'Anchorage en Alaska, est entré en éruption, selon l'USGS Volcano Center. Ce centre a enregistré quatre explosions entre 22H38 (22 mars) et 1h39 (23 mars) heure locale. Il a également émis une alerte volcanique et un code rouge pour l'aviation. Selon l'Alaska Volcano Observatory, une cinquième explosion a commencé à 4:38. Des cendres volcaniques sont tombées sur Skwentna et sont possibles sur Susitna Valley, d'après le National Weather Service. Les habitants de ces régions sont invités à réduire leurs déplacements et à rester chez eux. La dernière éruption du Mont Redoubt remonte à la fin 1989 : elle provoqua des coulées de boue qui avaient menacé une raffinerie. Elle éjecta des cendres volcaniques jusqu'à 14 000 m (45 000 pieds) d'altitude et un Boeing 747 de la KLM Royal Dutch Airlines fut pris dans son panache de cendres (le vol réussit à se poser à Anchorage). Les cendres couvrirent une zone d'environ 20 000 km².