June 21, 2012
Aleutian Island Volcano Erupts
Lee Rannals for redOrbit.com
If the Cleveland Volcano had any neighbors, then it decided to wake them up on Tuesday when the volcano shot off a thin cloud of ash several miles into the sky.
A pilot flying in the area estimated the ash cloud rose to 35,000 feet above sea level, according to the observatory.
However, Stephanie Prejean, a U.S. Geological Survey seismologist at the observatory in Anchorage, said satellite imagery shows only a weak ash signal.
"It was just one explosion, which was very typical of the thing Cleveland has been doing in the last year," Prejean told Reuters.
She said it´s possible the pilot's estimate is wrong, and the cloud rose to less than 35,000 feet.
Cleveland has been known to ooze out lava at times from its summit crater, but none of its small explosions have had clouds reach above 20,000 feet.
The observatory relies on satellite imagery, records lightning strikes, witness reports and other evidence to help it determine whether or not an eruption has taken place in the area.
Prejean said volcanoes closer to Anchorage have a seismic-monitoring network set up that allows scientists to see signals before eruptions happen.
Cleveland's volcanic activity had slowed down until Tuesday, so the Alaska Volcano Observatory lowered the alert level from the volcano to a "yellow" from an "orange" three weeks ago.
"Obviously, it has some oomph left in it," Tina Neal, an Alaska Volcano Observatory geologist, told Reuters.
Cleveland lies on an international flight path, so the Observatory has decided to raise the aviation alert level back up from yellow to orange.