ALASKA VOLCANO OBSERVATORY DAILY UPDATE
U.S. Geological Survey
Saturday, December 29, 2018, 11:24 AM AKST (Saturday, December 29, 2018, 20:24 UTC)

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

A short-duration explosion occurred at Cleveland last evening at 3:17 UTC December 29 (18:17 AKST December 28). A pilot report indicated an ash cloud to 17,000 ft (5.2 km) asl. The volcano was obscured by a high meteorological cloud deck with cloud tops at approximately 25,000 to 30,000 ft (7.6 to 9.1 km) asl. A lightning stroke was also detected providing further evidence that an ash emission occurred even though the volcanic cloud was not observed in satellite images. There have been no additional explosions detected since that time. Clouds continue to obscure views of Cleveland. These discrete, short-duration explosions are typical for Cleveland and present a hazard to aviation in the immediate vicinity of the volcano. Larger explosions that present a more widespread hazard to aviation are possible, but less likely and/or frequent.

Cleveland volcano is monitored by only one seismic station, 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.

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

Unrest at Veniaminof continues. A satellite image collected overnight shows barely elevated surface temperatures at the summit vent and web camera images from yesterday afternoon show no evidence of steam or ash emissions. Seismic tremor is at low levels. Taken together, these observations suggest that eruptive activity has greatly slowed or paused. Eruptive activity, consisting of resumed lava effusion and/or ash emissions could resume at any time without significant seismic precursors,

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.



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 with small earthquakes occurring. No activity was observed in cloudy 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, Acting 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.

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