ALASKA VOLCANO OBSERVATORY WEEKLY UPDATE
U.S. Geological Survey
Friday, May 1, 2009, 3:50 PM AKDT (Friday, May 1, 2009, 23:50 UTC)
60°29'7" N 152°44'38" W,
Summit Elevation 10197 ft (3108 m)
Current Volcano Alert Level: WATCH
Current Aviation Color Code: ORANGE
The 2009 eruption of Redoubt Volcano continues. During the past week, growth of the lava dome within the summit crater was confirmed by changes in the shape and size of the dome. Seismic activity remains elevated above background levels reflecting the ongoing process of dome growth and occasional rock falls and avalanches of hot blocks. Satellite images show persistent thermal anomalies, consistent with an actively growing lava dome in the summit crater. Occasional small rock avalanches from the lava dome have produced minor ash emissions in the immediate vicinity of the volcano. Such rock fall events have been observed in the Hut web camera and one was observed directly yesterday, by an AVO field crew, while at the camera station.
Clear web camera views this week have also shown a consistent gas and steam plume rising to about the summit of the volcano. Airborne gas measurements on April 28 indicate that emission of sulfur dioxide and carbon dioxide remain elevated and similar to previous measurements.
On Thursday April 30, AVO geologists sampled ash-fall deposits and worked on lahar deposits in the mid and lower Drift River Valley. Dome temperature measurements were made using a forward looking infrared (FLIR) camera and those data are being processed. In addition, the field crew retrieved and replaced data cards from three GPS stations.
The current Redoubt eruption is expected to continue for weeks to months. During this time, a cycle of relatively quiet periods of lava dome growth followed by explosive episodes of dome destruction will likely take place. Future explosions pose an ongoing threat of lahars in the Drift River Valley, trace to minor ash fall throughout south-central Alaska, and ash-related impacts to aviation. AVO is maintaining 24/7 operations in order to quickly detect renewed significant explosive activity and other hazardous phenomena.
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.
52°49'20" N 169°56'42" W,
Summit Elevation 5676 ft (1730 m)
Current Volcano Alert Level: UNASSIGNED
Current Aviation Color Code: UNASSIGNED
Based on the lack of volcanic activity since late January 2009, AVO lowered the Aviation Color Code and Alert Level at Cleveland volcano to UNASSIGNED earlier today. Because Cleveland is not monitored in real-time with a seismic network, we cannot confidently state that the volcano has returned completely to a background level of quiescence. Therefore, we use the term UNASSIGNED to characterize the state of the volcano and hazards.
OTHER ALASKA VOLCANOES
Seismic activity is monitored in real time at 31 volcanoes in Alaska. Satellite images of all Alaskan volcanoes are analyzed daily for evidence of ash plumes and elevated surface temperatures. Some volcanoes may currently display anomalous behavior but are not considered to be at a dangerous level of unrest. Akutan, Aniakchak, Augustine, Dutton, Fisher, Fourpeaked, Gareloi, Great Sitkin, Griggs, Iliamna, Isanotski, Kanaga, Katmai, Korovin, Mageik, Makushin, Martin, Novarupta, Okmok, Pavlof, Shishaldin, Snowy, Spurr, Tanaga, Trident, Ugashik-Peulik, Ukinrek Maars, Veniaminof, Westdahl, and Wrangell volcanoes are in color code GREEN
and volcano alert level Normal. All are at or near normal levels of background seismicity. AVO did not detect ash plumes or significant elevated surface temperatures in the vicinity of any volcano.
Please see http://www.avo.alaska.edu/color_codes.php
for complete definitions of Aviation color codes and Volcano alert levels.
VOLCANO INFORMATION ON THE INTERNET: http://www.avo.alaska.edu
RECORDING ON THE STATUS OF ALASKA'S VOLCANOES (907) 786-7478
Tom Murray, Scientist-in-Charge, USGS
firstname.lastname@example.org (907) 786-7497
Steve McNutt, Coordinating Scientist, UAF
email@example.com (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.