ALASKA VOLCANO OBSERVATORY WEEKLY UPDATE
U.S. Geological Survey
Friday, April 23, 2010, 12:27 PM AKDT (Friday, April 23, 2010, 20:27 UTC)
60°29'7" N 152°44'38" W,
Summit Elevation 10197 ft (3108 m)
Current Volcano Alert Level: NORMAL
Current Aviation Color Code: GREEN
AVO detected a series of small repetitive earthquakes near the summit of Redoubt volcano on April 17 - 20 of this week. This swarm was similar in character to those occurring on April 5 - 6, 2010 and in December 2009. As the lava dome and magma in the conduit system of Redoubt cool and continues to degas, it is possible that AVO will detect further short periods of increased shallow earthquake activity. There is no evidence to suggest that new magma is entering the system or the lava dome is becoming less stable. The Aviation Color Code and Volcano Alert Level at Redoubt Volcano remain at GREEN/NORMAL.
AVO will continue to monitor Redoubt closely, conduct aerial observations and gas measurements periodically, and watch for renewed signs of unrest.
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.
OTHER ALASKA VOLCANOES
Seismic activity is monitored in real time at 27 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, Augustine, Dutton, Fisher, Gareloi, Great Sitkin, Griggs, Iliamna, Isanotski, Kanaga, Katmai, Mageik, Makushin, Martin, Novarupta, Okmok, Pavlof, Shishaldin, Snowy, Spurr, Tanaga, Trident, Ugashik-Peulik, Ukinrek Maars, 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 of these volcanoes.
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
Chris Waythomas, Acting Scientist-in-Charge, USGS
firstname.lastname@example.org (907) 786-7497
Jessica Larsen, Acting Coordinating Scientist, UAFGI
email@example.com (907) 474-7992
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.