ALASKA VOLCANO OBSERVATORY WEEKLY UPDATE
U.S. Geological Survey
Friday, April 16, 2010, 3:02 PM AKDT (Friday, April 16, 2010, 23:02 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
Seismicity at Redoubt Volcano is currently at background. The swarm of more frequent, small, shallow seismic events detected on April 5 and 6 ended about 24 hours after onset with no noticeable change at the Redoubt lava dome. Visual observations, gas measurements, seismicity, and deformation data do not suggest an influx of new magma or any destabilization of the lava dome. Based on this, AVO lowered the Aviation Color Code and Volcano Alert Level at Redoubt Volcano to GREEN/NORMAL on Monday of this week.
The cause of these shallow, small seismic events at Redoubt remains uncertain. The early April sequence was very similar to a burst of seismicity in late December 2009. As the lava dome and magma in the conduit system of Redoubt continues to cool and degas, it is possible that AVO will detect further short periods of increased shallow earthquake activity. This type of activity likely will be inconsequential and not lead to further unrest or eruption.
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, UAF
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.