Satellite images show eruption on Alaska volcano

The eruption at Cleveland Volcano is a slow effusion of magma that is forming a lava dome, and not an explosive eruption that generates large ash plumes, said John Power, the scientist-in-charge at the Alaska Volcano Observatory.

"So far, it's just lava as far as we can tell from our satellite imagery and the people who have managed to see it from passing airplanes," he said.

The volcano is in a very remote area, on uninhabited Chuginadak Island, and that lowers the danger level.

"Certainly, if there were people who were going to be in the area, they would need to be concerned but there aren't many of those folks there right now," he said.

Currently the lava dome is confined within the summit crater. Power said the biggest danger would be if the lava dome began to grow large enough to spill out, then it could begin to generate ash-producing explosions.

"If it were to explode and push a bunch of ash up into the flight levels, then it would be a much more dangerous situation," he said.

Based upon past observations at several volcanoes, dome growth like this can go on for weeks to months.

"It's something we're going to be watching very closely, or as close as we can given our operational constraints there," he said.

There is no real-time seismic network at the volcano, located in the Aleutian Islands 939 miles southwest of Anchorage. Officials are not able to track local earthquake activity related to volcanic unrest. For pictures, they also have to rely on satellite imagery or what people in airplanes snap as they pass the volcano and send to the observatory.

Given the current level of activity and hazards, he said they don't plan to fly to the volcano, especially considering the expense.

But weather has cleared in the last few days to allow better satellite imagery.

"We've had a few good days where the top of the volcano has been sticking out of the clouds, so things are looking nice for us in terms of direct observations," Power said.

Short-lived explosions with ash clouds or plumes exceeding 20,000 feet above sea level are frequent on Cleveland. It last showed signs of unrest last summer, with a small ash emission and lava flows on its upper flanks.

The observatory says the last significant eruption of the 5,676-foot volcano began in February 2001 and eventually produced a lava flow that reached the ocean.

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