Michelle Coombs, a research geologist for the Alaska Volcano Observatory in Anchorage, said she got a firsthand look at the volcano this week. It looked much like it has in previous flights, except that there was less snow on the summit, perhaps due to increased activity at the top, she said.
"We are keeping our eyes on things very closely," Coombs said Friday.
New seismic instruments were installed on the Cook Inlet volcano's lower flanks during flights Tuesday and Wednesday, she said.
The 4,134-foot volcano hasn't sent out such strong signs since it last erupted in 1986, when ash from a 7-mile-high column drifted over Anchorage, the state's most populous city, and kept flights out of the skies over Cook Inlet.
The new observations suggest that the volcano is producing new magma. A thermal camera held outside a helicopter during one of the flights this week measured the temperature of steam coming from one of the vents at 750 degrees - well above the average temperature, Coombs said.
"It is heating up," she said. "It is very hot."
Seismic activity also increased slightly this week over last week. However, it remains well below what was observed just prior to the major eruption in 1986.
During Wednesday's flight, the amount of sulfur dioxide coming from the volcano was measured, showing a tenfold increase, Coombs said. The presence of sulfur indicates that the molten rock is moving closer to the volcano's surface.
Even given the volcano's increased unrest, there is no indication that a large eruption is imminent. Scientists expect the volcano to become even more active before it can be determined if it will erupt in any major way, Coombs said.
Augustine continues to be rated yellow, meaning eruptions are considered possible in the next few weeks and could occur with little or no warning. Its rating was moved from green to yellow in late August. The volcano is 75 miles southwest of Homer.
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