Volcano Update from Archive

Sunday, January 25, 2009 4:28 PM AKST (Monday, January 26, 2009 0128 UTC)

Redoubt Volcano
60°29'7" N 152°44'38" W, Summit Elevation 10197 ft (3108 m)
Current Volcano Alert Level: WATCH
Current Aviation Color Code: ORANGE

Unrest at Redoubt Volcano continues. AVO conducted an overflight of the volcano this afternoon, and observations confirm that an eruption has not occurred. Increased steaming through previously observed sources in the snow and ice cover were seen and sulfur gas emissions were noted. There was no significant disruption of the glacial ice, nor any apparent increased water discharge down the Drift River.

Seismicity remains well above background levels. Beginning at 00:58 AST (9:58 UTC) this morning, nearly continuous volcanic tremor was recorded at stations near Redoubt's summit, prompting AVO to raise the Aviation Color Code to ORANGE and the Alert Level to WATCH at 02:09 AST (11:09 UTC). Seismicity began to decline at about 05:30 AST (14:30 UTC) this morning, but remains elevated as of this writing.

The current activity at Redoubt could be precursory to an eruption, perhaps within hours to days. A further increase in seismicity is expected to accompany an eruption. Staff are currently monitoring the volcano 24 hours a day.

AVO raised the Aviation Color Code to YELLOW and the Volcano Alert Level to ADVISORY on November 5, 2008, in response to increased emissions of SO2, H2S, and CO2; melting of snow and ice near the volcano’s summit; and a subtle increase in seismicity. These observations reflected a change in the volcano’s hydrothermal system, possibly associated with an influx of new magma beneath the volcano. It is also possible that the change was related to the development of a new pathway of heated fluids rising from magma intruded during the 1989-90 eruption.

Tom Murray, Scientist-in-Charge, USGS

tlmurray@usgs.gov (907) 786-7497

Steve McNutt, Coordinating Scientist, UAF

steve@giseis.alaska.edu (907) 474-7131

The Alaska Volcano Observatory is a cooperative program of the U.S. Geological Survey, the University of Alaska Fairbanks Geophysical Institute, and the Alaska Division of Geological and Geophysical Surveys.