By Yereth Rosen
Anchorage, Alaska, - Mount Redoubt volcano has erupted for the first time in 20 years, threatening air traffic and nearby villages with a towering burst of ash, and more eruptions are expected.
The first blast occurred at 10:38pm Pacific time on Sunday, the Alaska Volcano Observatory said. It was followed by four smaller eruptions.
The 3 108m volcano, in a sparsely populated area 170km southwest of Anchorage, had been showing signs of a possible eruption for about two months. So far Anchorage has been untouched by harmful volcanic ash, which is drifting north from the volcano.
"We expect the pattern of this event to be similar to the 1989 and 1990 eruptions and the activity could continue along those lines for several weeks or several months," said US Secretary of the Interior Ken Salazar.
The volcano last rumbled to life in December 1989, erupting multiple times over a period of almost five months, with ash from the first blast nearly downing a KLM jetliner.
Ash can hamper visibility, clog machinery, hinder breathing and damage wastewater systems, among other things.
Tina Neal, a geologist at the Alaska Volcano Observatory, said each of the five eruptions lasted 10-20min and the series ended around 4.31am on Monday.
"Each event sent up an ash cloud as high as 15 000m and possibly 18 300m," Neal said.
The observatory warned airlines to steer clear of the area. Anchorage-area airports are still open, but Alaska Air Group Inc - the state's leading carrier - said it had canceled 19 flights in and out of Anchorage so far.
"This is changing constantly, depending on how the winds blow," said Alaska Airlines spokeswoman Marianne Lindsey.
The Drift River Oil Terminal, a holding point for crude oil near the foot of the volcano on the western shore of Cook Inlet, was shutting down temporarily.
"We believe that everything is safe there now," Salazar said. The terminal was inundated by floods and mudslides during the 1989-1990 eruptions.
It's owned and operated by Cook Inlet Pipe Line Co, which is partly owned by Unocal, now a part of oil giant Chevron Corp.
The bulk of the ash from the most recent eruptions was blown at the 9 m level and wasn't reaching significantly populated areas, Neal said.
Ash was confirmed in one community and reported in a few other spots along the Susitna Valley north of Anchorage, she added. Denali Park and Nikolai also experienced some ash fall.
"We should consider ourselves lucky today that we aren't out sweeping up ash in Anchorage," said John Power, a geophysicist at the Alaska Volcano Observatory.
"If Redoubt erupts again, next time the wind direction may be very different," said Power, who expects more eruptions.
"The volcano is still restless," said Neal. "We'll be watching it very closely. It is highly unstable still and further eruptions are likely." - Reuters