Printer friendly versionAVO/USGS Volcanic Activity Notice
Current Volcano Alert Level: WATCH
Previous Volcano Alert Level: WARNING
Current Aviation Color Code: ORANGE
Previous Aviation Color Code: REDIssued
: Friday, April 3, 2009, 11:44 AM AKDT (20090403/1944Z)Source
: Alaska Volcano ObservatoryNotice Number
: N 60 deg 29 min W 152 deg 44 minElevation
: 10197 ft (3108 m)Area
: Cook Inlet-South Central AlaskaVolcanic Activity Summary
: The eruption of Redoubt Volcano continues. Over the past several days, the intensity of ash-production has decreased. Current observations indicate a lava dome is growing in the summit crater. Therefore, we are lowering the alert level and aviation color code.
The 2009 eruption is now characterized by continuous emission of steam, volcanic gas, and variable amounts of ash. These processes are occurring as effusion of lava in the summit crater produces a lava dome. While at this level of activity, trace amounts of ash and a perceptible volcanic haze layer may be intermittently present throughout south-central Alaska.
A growing lava dome is inherently unstable; a sudden dome collapse or explosion can occur with no warning and produce a more voluminous ash cloud that rises to elevations above 25,000 feet. If such an event is detected, AVO would issue appropriate warnings. Recent Observations
[Volcanic cloud height] Over the last few days, a diffuse cloud of volcanic gas, ash, and steam is rising to variable altitudes over the volcano, but mostly less than 15,000 feet above sea level. At times of more vigorous ash production, the cloud has risen as high as 25,000 feet.
[Ash fall] Trace amounts of ash fall (less than 0.8 mm or less than 1/32 inch) have been reported at Kenai and at Valdez. The area in the immediate vicinity of the volcano is blanketed by a thin layer of ash visible in the AVO web cameras.
[Lava flow/dome] AVO overflights and photography have confirmed that a lava dome is actively growing in the summit crater. Occasional avalanches of hot blocks tumbling from the dome are traveling a short distance down the north flank of the volcano.
[Mudflow] To our knowledge, no mudflows have occurred in the Drift River since the last significant explosion.
[Other volcanic cloud information] An intermittent volcanic haze has been reported over south central Alaska. This cloud likely consists of water vapor, small quantities of volcanic gases, aerosols, and ash. Hazard Analysis
[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.
[Ash cloud] Diffuse clouds containing trace amounts of ash and volcanic gas may be present downwind of the volcano.
[Lava flow/dome] A growing lava dome is inherently unstable and may produce explosions or avalanches of hot debris at any time.
[Mud flow] Additional mudflows may be produced by dome collapse events.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 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
email@example.com (907) 786-7497
Steve McNutt, Coordinating Scientist, UAF
firstname.lastname@example.org (907) 474-7131Next 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 athttp://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.