Re: Redoubt VAN/VONA issued Dec 28, 2009 09:53 ADT Volcano Alert Level ADVISORY - Aviation Color Code YELLOW

AVO is raising the Aviation Color Code to YELLOW and the Volcano Alert Level to ADVISORY at Redoubt volcano. At roughly 16:00 AKDT yesterday, Dec. 27 (0100 Dec. 28 UTC), a series of small repetitive earthquakes began occurring in the vicinity of the volcano's summit. Activity is continuing this morning. See http://www.avo.alaska.edu/webicorders/Redoubt/RSO_EHZ_AV.php

ALASKA VOLCANO OBSERVATORY WEEKLY UPDATE
Friday, January 1, 2010 11:57 AM (Friday, January 1, 2010 20:57 UTC)

REDOUBT VOLCANO (CAVW #1103-03-)
60°29'7" N 152°44'38" W, Summit Elevation 10197 ft (3108 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW

The swarm of shallow, small earthquakes that began last Sunday, December 27 at Redoubt Volcano has greatly diminished or ceased. Close-in aerial observations of the new lava dome yesterday indicated no disruption at the surface and no sign of instability. Photographs and thermal camera imaging of the 2009 lava dome showed continued high temperature areas on the surface of the dome which is expected as the thick pile of blocky lava slowly cools in place. Magmatic gas emission from the dome area, however, is somewhat elevated compared to the last measurement in early November.

The Aviation Color Code remains YELLOW and the Volcano Alert Level remains ADVISORY.

AVO is continuing to evaluate information to interpret this week's uptick in seismicity and gas output. One explanation involves input of new magma or remobilization of existing magma within volcano's shallow plumbing system. This process appears to have ceased or paused. It remains possible that activity could reappear, intensify and lead to additional eruptive activity. We would expect a sharp increase in seismicity and other marked changes prior to such activity.

AVO will continue to issue daily status reports as long as the Aviation Color Code and Alert Level are elevated.

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 10,197 feet above sea level. Recent eruptions occurred in 1902, 1966-68, 1989-90, and 2009. The 1989-90 and 2009 eruptions produced mudflows, or lahars, that traveled down the Drift River and partially flooded the Drift River Oil Terminal facility. The ash plumes produced by the 1989-90 and 2009 eruptions significantly disrupted air traffic and resulted in minor or trace amounts of ash in the city of Anchorage and other communities in south-central and interior Alaska.

The swarm of shallow, small earthquakes that began last Sunday, December 27 at Redoubt Volcano has greatly diminished or ceased. Close-in aerial observations of the new lava dome yesterday indicated no disruption at the surface and no sign of instability. Photographs and thermal camera imaging of the 2009 lava dome showed continued high temperature areas on the surface of the dome which is expected as the thick pile of blocky lava slowly cools in place. Magmatic gas emission from the dome area, however, is somewhat elevated compared to the last measurement in early November.

The Aviation Color Code remains YELLOW and the Volcano Alert Level remains ADVISORY.

AVO is continuing to evaluate information to interpret this week's uptick in seismicity and gas output. One explanation involves input of new magma or remobilization of existing magma within volcano's shallow plumbing system. This process appears to have ceased or paused. It remains possible that activity could reappear, intensify and lead to additional eruptive activity. We would expect a sharp increase in seismicity and other marked changes prior to such activity.

AVO will continue to issue daily status reports as long as the Aviation Color Code and Alert Level are elevated. 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 10,197 feet above sea level. Recent eruptions occurred in 1902, 1966-68, 1989-90, and 2009. The 1989-90 and 2009 eruptions produced mudflows, or lahars, that traveled down the Drift River and partially flooded the Drift River Oil Terminal facility. The ash plumes produced by the 1989-90 and 2009 eruptions significantly disrupted air traffic and resulted in minor or trace amounts of ash in the city of Anchorage and other communities in south-central and interior Alaska.