Alaska Volcano ObservatoryWeekly UpdateFriday, November 7, 2008 11:55 AM AKST (20:55 UTC)
REDOUBT VOLCANO (CAVW #1103-03-)
60°29'7" N 152°44'38" W, Summit Elevation 10197 ft (3108 m)
Current Aviation Color Code: YELLOW
Current Volcano Alert Level: ADVISORY
On Wednesday, November 5, 2008, AVO raised the Aviation Color Code to YELLOW and the Volcano Alert Level to ADVISORY owing to the several month long detection of potentially significant changes in gas emission and heat output from Redoubt Volcano. These changes are a departure from long-observed background activity. The remainder of the week seismic activity remained at low levels and satellite views of the volcano were partly cloudy with no activity observed. AVO staff began work to install additional geophysical equipment and a web camera on the volcano.
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. 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 plume 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.
OKMOK VOLCANO (CAVW #1101-29-)
53°23'49" N 168°9'58" W, Summit Elevation 3520 ft (1073 m)
Current Aviation Color Code: YELLOW
Current Volcano Alert Level: ADVISORY
Seismic activity at Okmok Volcano remained low all week with a few possible tremor bursts over the last 24-hour period. Throughout the week satellite views of the volcano were mostly cloudy with no activity observed.
Although the level of seismicity is relatively low, it is possible, but growing increasingly unlikely, that vigorous ash emissions will resume.
Okmok volcano is a 6-mile-wide caldera that occupies most of the eastern end of Umnak Island, located 75 miles southwest of Dutch Harbor in the eastern Aleutian Islands. Okmok has had several eruptions in historic time typically consisting of ash emissions occasionally to over 30,000 feet ASL but generally much lower; lava flows crossed the caldera floor in 1945, 1958, and 1997.
The nearest settlement is Nikolski, population about 35, roughly 45 miles west of the volcano. A ranch caretaker family lives at Fort Glenn on the flank of the volcano about 6 miles east of the caldera rim.
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. Augustine, Iliamna, Wrangell, Gareloi, Great Sitkin, Makushin, Fisher, Shishaldin, Isanotski, Pavlof, Veniaminof, Ugashik-Peulik, Griggs, Snowy, Fourpeaked, Aniakchak, Tanaga, Kanaga, Akutan, Westdahl, Dutton, Ukinrek Maars, Martin, Mageik, Trident, Katmai, Novarupta, Spurr, and Korovin 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
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.
