ALASKA VOLCANO OBSERVATORY DAILY UPDATE
U.S. Geological Survey
Thursday, January 19, 2017, 1:05 PM AKST (Thursday, January 19, 2017, 22:05 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

Volcanic unrest continues at Bogoslof volcano. No new ash emissions have been observed since the 13:20 AKST 18 January (22:20 UTC) eruption and seismicity remains low, so the color code was lowered to ORANGE.

Following an approximately 20-minute-long increase in seismic activity, Bogoslof erupted yesterday afternoon at about 13:20 AKST 18 January (22:20 UTC). Pilots reported the cloud reached a height greater than 31,000 ft asl., and prevailing winds carried it northeast over the Bering Sea. This eruption also produced lightning strikes, and infrasound signals detected by sensors in Sand Point and Dillingham.

A satellite image from 13:26 AKST 18 January (22:26 UTC), just after this event, showed a dark ash cloud just northeast of Bogoslof. This cloud was darker in color, and presumably more ash-rich, than others we have seen in the eruptive sequence, which began in mid-December 2016. This image also suggests the presence of very hot material (lava) at the surface immediately surrounding the vent – the first such observation during this eruption sequence. This is also the first eruption since the 31 December 2016 event to produce detectable SO2 in satellite data.

Following the initial explosive eruption, a second, lower-level volcanic cloud is visible in satellite images around 14:00 AKST (23:00 UTC), likely corresponding with an increase in seismic tremor that occurred from 13:40-13:55 AKST (22:40-22:55 UTC). This event was also detected on distant infrasound sensors but did not produce reported lightning. Seismicity remained elevated until 15:45 AKST (00:45 19 January UTC), but no additional eruption clouds have been observed.

Bogoslof volcano is currently quiet, but given the pattern of eruptive activity over the past month the volcano likely remains in a restless and unpredictable condition and additional eruptive bursts accompanied by volcanic clouds could occur at any time.

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.

PAVLOF VOLCANO (VNUM #312030)
55°25'2" N 161°53'37" W, Summit Elevation 8261 ft (2518 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW

Nothing significant was detected in seismic or pressure sensor data during the past 24 hours. Nothing noteworthy observed in clear to cloudy satellite images of the volcano. A small plume from the summit was observed yesterday evening in web camera views.

The degree of unrest at Pavlof can change quickly. A return to eruptive activity can occur with with little or no warning.

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

Nothing of note has been observed in satellite views of Cleveland volcano over the past day. Clear views of the summit in local web camera images showed a low-level steam plume emanating from the summit crater. No significant activity was observed in seismic or pressure sensor data during the past 24 hours.

OTHER ALASKA VOLCANOES

Other Alaska volcanoes show no signs of significant unrest: http://www.avo.alaska.edu/activity/

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

FOR MORE INFORMATION ON ALASKA VOLCANOES: http://www.avo.alaska.edu

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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