Volcano Update from Archive



ALASKA VOLCANO OBSERVATORY INFORMATION STATEMENT
Sunday, January 25, 2009 6:57 AM AKST (Sunday, January 25, 2009 1557 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

Over the past 48 hours, seismic activity at Redoubt Volcano has increased markedly. This has taken the form of periodic tremor bursts that are most visible on the two seismic stations closest to the summit. Beginning at 00:58 AKT (9:58 UTC) this morning, tremor became sustained and its amplitude increased markedly. AVO raised the Aviation Color Code to ORANGE and the Alert Level to WATCH this morning at 2:09 AKT (11:09 UTC).



This activity could be precursory to an eruption, perhaps within hours to days. A further increase in seismicity is expected to accompany an eruption. There is no indication that the volcano is currently erupting.



At this time, clouds obscure the volcano in satellite views, but NEXRAD weather radar data show no signs eruptive activity. AVO has received no recent observer reports. 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.



Typical eruptions of Redoubt are characterized by large explosions that produce ash clouds reaching as high as 40,000 ft asl. Explosive events are generally separated by growth of a lava dome in the volcano’s summit crater. Past eruptions of Redoubt have continued for months to years. Previous historical eruptions have deposited several millimeters of ash on the Kenai Peninsula and trace amounts of ash in Anchorage; the 1989-90 eruption also affected international air traffic. Other hazards include pyroclastic flows that may travel several miles from the volcano, especially to the north, and volcanic mudflows, or lahars, that can travel many miles from their source. In 1989-90, 35 lahars flowed east down the Drift River, at least three of which reached Cook Inlet and partially flooded the Drift River Oil Terminal facility.



Heavily ice-mantled Redoubt volcano is located on the western side of Cook Inlet, 170 km (106 mi) southwest of Anchorage and 82 km (51 mi) west of Kenai, within Lake Clark National Park. Redoubt is a stratovolcano which rises to 10,198 feet above sea level. Recent eruptions occurred in 1902, 1966-68, and 1989-90.

CONTACT INFORMATION:
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.