ALASKA VOLCANO OBSERVATORY DAILY UPDATE
U.S. Geological Survey
Saturday, February 4, 2017, 11:10 AM AKST (Saturday, February 4, 2017, 20:10 UTC)

BOGOSLOF VOLCANO (VNUM #311300)
53°55'38" N 168°2'4" W, Summit Elevation 492 ft (150 m)
Current Volcano Alert Level: WATCH
Current Aviation Color Code: ORANGE

Two eruptive episodes from Bogoslof Volcano occurred yesterday. The first episode was detected on seismic instruments beginning at 4:57, February 3 AKST (13:52 UTC). No ash cloud was seen in satellite imagery but the activity was seen on infrasound instruments indicating that a likely low-level emission had occurred. An increase in seismic tremor was again detected on seismic instruments at 18:41 February 3 AKST (1:41 February 4 UTC) and was also seen on infrasound instruments. Satellite observations and pilot reports confirmed a small volcanic ash plume below 25,000 feet above sea level and tracking to the north. By 20:20 AKST the cloud was no longer distinguishable from the meteorological clouds. Seismicity through this morning has been quiet. No activity has been detected in partly cloudy satellite data.

Bogoslof volcano remains at a heightened state of unrest and in an unpredictable condition. Additional explosions producing high-altitude volcanic clouds could occur at any time. Some previous explosions have been preceded by an increase in earthquake activity that allowed for short-term forecasts of imminent significant explosive activity. Although we are able to detect energetic explosive activity in real-time, there is typically a lag of tens of minutes until we can characterize the magnitude of the event and the altitude of the volcanic cloud. Low-level explosive activity that is below our ability to detect in our data sources may be occurring. These low-level explosions could pose a hazard in the immediate vicinity of the volcano. When such low-level activity occurs, it is considered to be consistent with Aviation Color Code ORANGE and Volcano Alert Level WATCH.

AVO has no ground-based volcano monitoring equipment on Bogoslof volcano. We continue to monitor satellite images, information from the Worldwide Lightning Location Network pertaining to volcanic-cloud lightning, and data from seismic and infrasound instruments on nearby islands for indications of volcanic activity.

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

The observation of a new lava dome partially filling the summit crater at Cleveland volcano in recent satellite observations prompted AVO to raise the Aviation Color Code to ORANGE and the Alert Level to WATCH yesterday. Cloudy weather has obscured the volcano in satellite and web camera images over the past day. No significant activity observed in seismic or pressure sensor data during the past 24 hours.

TAKAWANGHA VOLCANO (VNUM #311090)
51°52'1" N 178°1'37" W, Summit Elevation 4754 ft (1449 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW

The energetic earthquake swarm on Tanaga Island that began on January 23, 2017 is ongoing but continues at a decreased rate and intensity. No activity has been detected in cloudy satellite views over the past day.

OTHER ALASKA VOLCANOES

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

AVO scientists conduct daily checks of earthquake activity at all seismically-monitored volcanoes, examine web camera and satellite images for evidence of airborne ash and elevated surface temperatures, and consult other monitoring data as needed.

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

Jeff Freymueller, Coordinating Scientist, UAFGI
jfreymueller@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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