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ALASKA VOLCANO OBSERVATORY DAILY UPDATE
U.S. Geological Survey
Thursday, December 6, 2018, 12:12 PM AKST (Thursday, December 6, 2018, 21:12 UTC)


SEMISOPOCHNOI VOLCANO (VNUM #311060)
51°55'44" N 179°35'52" E, Summit Elevation 2625 ft (800 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW

Unrest continues at Semisopochnoi volcano. No eruptive activity was observed in mostly cloudy satellite views of the volcano over the past day. Local seismic data remains offline.

Semisopochnoi is monitored with an on-island seismic network, though this is currently off-line, and remotely by satellite and lightning sensors. Furthermore, an infrasound array on Adak Island may detect explosive emissions from Semisopochnoi with a 13 minute delay if atmospheric conditions permit.


VENIAMINOF VOLCANO (VNUM #312070)
56°11'52" N 159°23'35" W, Summit Elevation 8225 ft (2507 m)
Current Volcano Alert Level: WATCH
Current Aviation Color Code: ORANGE

Veniaminof volcano continues to exhibit unrest characterized by the slow effusion of lava from the intra-caldera cone. Elevated surface temperatures have been observed in satellite views of the volcano over the past day consistent with the presence of lava at the surface. High-resolution satellite images acquired on December 2 and 5, 2018 show a third lobe of lava extending a short distance down the southeast flank of the intracaldera cone. The three lava lobes are generating impressive steam emissions due to their interaction with snow and ice. These emissions have been visible this morning in web camera views of the volcano. No acoustic signals have been recorded by regional infrasound sensors over the past 24 hours. The steady, low-level, seismic tremor that has characterized the eruption thus far has declined somewhat over the past 10-12 hours and may indicate that the effusion of lava has also declined.

Veniaminof volcano is monitored with a local real-time seismic network, which will typically allow AVO to detect changes in unrest that may lead to a more significant explosive eruption. AVO combines seismic, infrasound, lightning, and satellite data for rapid detection of such events.


CLEVELAND VOLCANO (VNUM #311240)
52°49'20" N 169°56'42" W, Summit Elevation 5676 ft (1730 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW

Low-level unrest continues at Cleveland volcano. No significant activity has been detected in seismic or regional infrasound data over the past day. Slightly elevated surface temperatures at the summit were observed in a few satellite images over the past day.

Cleveland volcano is monitored by only two seismic stations, which restricts AVO's ability to detect precursory unrest that may lead to an explosive eruption. Rapid detection of an ash-producing eruption may be possible using a combination of seismic, infrasound, lightning, and satellite data. The web camera, one seismic station, and the local infrasound array are offline due to a equipment failure on September 23rd. This hampers efforts to rapidly detect explosive activity; however, Cleveland remains monitored with a single seismic station and regional instruments.


GREAT SITKIN VOLCANO (VNUM #311120)
52°4'35" N 176°6'39" W, Summit Elevation 5709 ft (1740 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW

Low-level unrest continues at Great Sitkin volcano. Small earthquakes associated with the ongoing unrest continue to be recorded on the local seismic network. No activity was observed in satellite views of the volcano over the past day. No explosive activity was detected on a regional infrasound array on Adak Island.

Great Sitkin volcano is monitored with a local real-time seismic network, which will typically allow AVO to detect changes in unrest that may lead to an explosive eruption. Rapid detection of an ash-producing eruption would be accomplished using a combination of seismic, infrasound, lightning, and satellite data.


OTHER ALASKA VOLCANOES

Information on all Alaska volcanoes is available at : http://www.avo.alaska.edu.

For definitions of Aviation Color Codes and Volcano Alert Levels, see: http://www.avo.alaska.edu/color_codes.php

SUBSCRIBE TO VOLCANO ALERT MESSAGES by email: http://volcanoes.usgs.gov/vns/

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CONTACT INFORMATION:

Michelle Coombs, Scientist-in-Charge, USGS
mcoombs@usgs.gov (907) 786-7497

David Fee, Coordinating Scientist, UAFGI
dfee1@alaska.edu (907) 322-4085


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.