Printer friendly versionALASKA VOLCANO OBSERVATORY
Friday, April 28, 2006 2:25 PM AKDT (2225 UTC)
59°21'48"N 153°26'W , Summit Elevation 4134 ft (1260 m)
Current Level of Concern Color Code: YELLOW
Based on the current level of activity at Augustine, AVO lowered the Level of Concern Color Code from ORANGE to YELLOW earlier today.
Data and observations currently indicate that the growth of the summit lava dome and lava flows has stopped, or continues only at a very low rate. Seismic data show that rock fall and avalanche events are still occurring, but at a diminished level. Visual observations and satellite data show that there have not been any detectable changes at the summit over the last few weeks.
Despite the apparent cessation of lava dome growth, the new dome and lava flows are still highly unstable, and rock falls and avalanches are still occurring and may continue for several weeks or months. The north flank of the island is the area most susceptible to rock falls and avalanches, and the steep ends of the lava flows are also places where rock fall activity may continue. These areas are considered very hazardous. Small, dilute ash clouds produced by rock falls and avalanches may still develop, but these ash clouds are unlikely to extend beyond Augustine Island.
Some indicators suggest that magma is still present at shallow levels. AVO will continue to make volcanic gas measurements and recent measurements indicate that levels are still above background and likely indicate degassing of shallow magma. Weak thermal anomalies persist in satellite data, consistent with slow cooling of the lava dome and continued venting of hot gases.
Despite the volcano's current quiet state, renewed eruptive activity is possible. AVO expects that a renewal of explosive activity or lava extrusion would likely be preceded by increases in seismicity, gas output, and deformation.
Brief, unexpected explosions are still possible if hot gas and rocks interact with groundwater, but such explosions are unlikely to produce ash that would travel far beyond the island.
AVO continues to monitor Augustine closely and the observatory will remain staffed 24/7 until conditions at the volcano approach background levels.
56°11'44"N 159°23'18"W , Summit Elevation 8225 ft (2507 m)
Current Level of Concern Color Code: YELLOW
Seismicity at Veniaminof remained low this week. A steam plume possibly containing minor amounts of ash was visible earlier in the week. Production of short-lived, very small-volume steam and ash bursts from the intracaldera cone has been typical of this volcano intermittently over the past few years. There are no indications that a larger eruption is imminent. Ash clouds and fallout from these events are not likely to extend beyond the caldera rim, but could pose a hazard to people and low-flying aircraft in the vicinity of the active cone.
OTHER ALASKA VOLCANOES
Seismic activity is monitored in real time at 30 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. Wrangell, Spurr, Redoubt, Iliamna, Snowy, Griggs, Katmai, Novarupta, Trident, Mageik, Martin, Peulik, Ukinrek Maars, Aniakchak, Pavlof, Dutton, Isanotski, Shishaldin, Fisher, Westdahl, Akutan, Makushin, Okmok, Korovin, Great Sitkin, Kanaga, Tanaga, and Gareloi volcanoes are in color code GREEN. 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.
ABBREVIATED COLOR CODE KEY
(contact AVO for complete description):
GREEN volcano is dormant; normal seismicity and fumarolic activity occurring
YELLOW volcano is restless; eruption may occur
ORANGE volcano is in eruption or eruption may occur at any time
RED significant eruption is occurring or explosive eruption expected at any time
VOLCANO INFORMATION ON THE INTERNET: http://www.avo.alaska.edu
RECORDING ON THE STATUS OF ALASKA'S VOLCANOES (907) 786-7478
Chris Waythomas, Scientist-in-Charge, USGS
firstname.lastname@example.org (907) 786-7497
Chris Nye, Coordinating Scientist, UAF-GI
email@example.com (907) 474-7430
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.