ALASKA VOLCANO OBSERVATORY STATUS REPORT
U.S. Geological Survey
Wednesday, January 18, 2017, 6:25 PM AKST (Thursday, January 19, 2017, 03:25 UTC)

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

Following an approximately 20-minute-long increase in seismic activity, Bogoslof erupted this afternoon at about 13:20 AKST (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 (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.

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.

The Aviation Color Code remains at RED and the Alert Level remains at WARNING.

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

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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