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AVO/USGS Volcanic Activity Notice

Volcano: Redoubt (CAVW #1103-03-)

Current Volcano Alert Level: WATCH
Previous Volcano Alert Level: WARNING

Current Aviation Color Code: ORANGE
Previous Aviation Color Code: RED

Issued: Monday, April 6, 2009, 2:55 PM AKDT (20090406/2255Z)
Source: Alaska Volcano Observatory
Notice Number: 2009/A34
Location: N 60 deg 29 min W 152 deg 44 min
Elevation: 10197 ft (3108 m)
Area: Cook Inlet-South Central Alaska

Volcanic Activity Summary: The eruption of Redoubt continues with varying intensity of ash and lava production from the summit crater. Additional significant explosive events with accompanying ash clouds, ash fall, and mudflows are possible and can occur with little or no warning. Visual, satellite, and seismic observations indicate that a lava dome is again forming in the summit crater.

The character of current seismicity suggests that a sudden explosive eruption is not imminent. Present levels of activity are emitting only a very minor amount of ash that poses a hazard of limited aerial extent. Consequently, AVO is lowering the Aviation Color Code to ORANGE and the Alert Level to WATCH. AVO will maintain 24/7 operations in order to quickly detect renewed significant explosive activity and other hazardous phenomena.

Intermittent views by the AVO web camera earlier today show a continuous plume composed primarily of water vapor and gas rising above the summit to less than 15,000 feet and drifting northeast.

Please see the National Weather Service Redoubt coordination page http://pafc.arh.noaa.gov/volcano.php for the latest ash fall information.

Recent Observations:
[Volcanic cloud height] Unknown. Web camera views of the volcano are obscured.
[Monitoring report] Shallow seismicity continues beneath the summit crater. High levels of gas emissions have been measured during the past few days.
[Other volcanic cloud information] Interaction of hot debris from the explosive event on Saturday, April 4th with snow, ice, and water may produce occasional small ash and steam plumes above the north flank of the volcano.
[Ash fall] While this type of activity persists, low-level clouds consisting of minor amounts of ash and volcanic gas may extend downwind for tens of miles and drop trace amounts of ash on communities.
[Mudflow] Additional mudflows may be produced by sudden dome collapse events or outbursts of water from the summit crater.

Remarks: 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, and 1989-90. The 1989-90 eruption 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 eruption affected international air traffic and resulted in minor or trace amounts of ash in the city of Anchorage and other nearby communities.

Contacts: Tom Murray, Scientist-in-Charge, USGS
tlmurray@usgs.gov (907) 786-7497

Steve McNutt, Coordinating Scientist, UAF
steve@giseis.alaska.edu (907) 474-7131

Next Notice: A new VAN will be issued if conditions change significantly or alert levels are modified. While a VAN is in effect, regularly scheduled updates are posted at
http://www.avo.alaska.edu

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.
(1) VOLCANO OBSERVATORY NOTICE FOR AVIATION (VONA)
(2) Issued:(20090406/2255Z)
(3) Volcano:Redoubt (CAVW# 1103-03-)
(4) Current Color Code:ORANGE
(5) Previous Color Code:red
(6) Source:Alaska Volcano Observatory
(7) Notice Number:2009/A34
(8) Volcano Location:N 60 deg 29 min W 152 deg 44 min
(9) Area:Cook Inlet-South Central Alaska
(10) Summit Elevation:10197 ft (3108 m)
(11) Volcanic Activity Summary:The eruption of Redoubt continues with varying intensity of ash and lava production from the summit crater. Additional significant explosive events with accompanying ash clouds, ash fall, and mudflows are possible and can occur with little or no warning. Visual, satellite, and seismic observations indicate that a lava dome is again forming in the summit crater.

The character of current seismicity suggests that a sudden explosive eruption is not imminent. Present levels of activity are emitting only a very minor amount of ash that poses a hazard of limited aerial extent. Consequently, AVO is lowering the Aviation Color Code to ORANGE and the Alert Level to WATCH. AVO will maintain 24/7 operations in order to quickly detect renewed significant explosive activity and other hazardous phenomena.

Intermittent views by the AVO web camera earlier today show a continuous plume composed primarily of water vapor and gas rising above the summit to less than 15,000 feet and drifting northeast.

Please see the National Weather Service Redoubt coordination page http://pafc.arh.noaa.gov/volcano.php for the latest ash fall information.
(12) Volcanic cloud height:Unknown. Web camera views of the volcano are obscured.
(13) Other volcanic cloud information:Interaction of hot debris from the explosive event on Saturday, April 4th with snow, ice, and water may produce occasional small ash and steam plumes above the north flank of the volcano.
(14) Remarks: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, and 1989-90. The 1989-90 eruption 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 eruption affected international air traffic and resulted in minor or trace amounts of ash in the city of Anchorage and other nearby communities.
(15) Contacts:Tom Murray, Scientist-in-Charge, USGS
tlmurray@usgs.gov (907) 786-7497

Steve McNutt, Coordinating Scientist, UAF
steve@giseis.alaska.edu (907) 474-7131
(16) Next Notice:A new VONA will be issued if conditions change significantly or alert levels are modified. While a VONA is in effect, regularly scheduled updates are posted at
http://www.avo.alaska.edu