No doubt, Alaska's Redoubt Volcano will Erupt at any Moment

ANCHORAGE, Alaska, March 25 (UPI) -- A small explosion at Mount Redoubt in Alaska early Wednesday sent up an ash cloud 15,000 feet that dissipated over the volcano, scientists say.

Mount Redoubt began erupting Sunday and has now had seven explosions. But scientists say the seventh was considerably smaller than the other six, the Anchorage Daily News reported.

"It was such a minor eruption, we almost didn't see it on the radar," National Weather Service meteorologist Christian Cassell said.

There was no ash advisory and the explosion did not interrupt air traffic as previous ones have.

Peter Cervelli of the Alaska Volcano Observatory said that Redoubt is "extruding a lava dome."

"We may have had a piece of that dome break off and tumble along and produce an ash cloud," he said.

Mount Redoubt is on the Kenai Peninsula, about 110 miles southwest of Anchorage

Alaska's Redoubt Volcano, 100 miles southwest of Anchorage, is expected to erupt within days or weeks, authorities at the Alaska Volcano Observatory say.

"The level of seismic activity" has "increased markedly" in recent days at Mount Redoubt, according to the Observatory.

From the Alaska Volcano Observatory:

Summary of Current Unrest

Since last fall, the Alaska Volcano Observatory (AVO) has detected increasing volcanic unrest at Redoubt Volcano. Starting on Friday, January 23, the level of seismic activity increased markedly, and on Sunday AVO raised the Aviation Color Code to ORANGE and the Volcano Alert Level to WATCH. On the basis of all available monitoring data AVO regards that an eruption similar to or smaller than the one that occurred in 1989-90 is the most probable outcome. We expect such an eruption to occur within days to weeks.

Alaska's volcanoes are potentially hazardous to passenger and freight aircraft as jet engines sometimes fail after ingesting volcanic ash. On December 15, 1989, a Boeing 747 flying 240 kilometers (150 miles) northeast of Anchorage encountered an ash cloud erupted from Redoubt Volcano and lost power in all four jet engines. The plane, with 231 passengers aboard, lost more than 3,000 meters (~9,800 feet) of elevation before the flight crew was able to restart the engines (Casadevall, 1994). After landing, it was determined the airplane had suffered about $80 million in damage (Brantley, 1990).

Mount Redoubt, or Redoubt Volcano, is an active stratovolcano in the largely volcanic Aleutian Range of Alaska. The mountain is also the highest within the range, and among the highest peaks in Alaska. It is located in the Chigmit Mountains (a subrange of the Aleutians), west of Cook Inlet, about 180 km (110 miles) southwest of Anchorage, Alaska. The Alaska Volcano Observatory currently rates Redoubt as Aviation Alert Level Orange and Volcano Alert Level Watch. On January 25, 2009, the Alaska Volcano Observatory warned that Redoubt may erupt within "hours or days". On January 28, 2009, the AVO released an information statement stating that an eruption similar to its 1989/1990 event is the most likely scenario.

Mount Redoubt erupted in 1902, 1966 and 1989. The eruption in 1989 spewed volcanic ash to a height of 14,000 m (45,000 ft) and managed to catch KLM Royal Dutch Airlines flight 867, a Boeing 747 aircraft, in its plume (the flight landed safely at Anchorage). The ash covered an area of about 20,000 km² (7,700 sq. miles). The 1989 eruption is also notable for being the first ever volcanic eruption to be successfully predicted by the method of long-period seismic events developed by Swiss/American volcanologist Bernard Chouet.