ALASKA VOLCANO OBSERVATORY DAILY UPDATE
U.S. Geological Survey
Monday, August 7, 2017, 3:23 PM AKDT (Monday, August 7, 2017, 23:23 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

An explosive eruption began this morning at about 10:00 AM AKDT (18:00 UTC) and continued through about 13:00 AKDT (21:00 UTC) as indicated in seismic, infrasound, satellite, and lightning data. Since that time, seismic and infrasound activity have declined, but are still above background. Low-level ash emissions may still be occurring, and could intensify again at any time.

Today's eruption is longer-lived than most of the events in the eruptive sequence that started in December 2016. Satellite images show that ash from the eruption is forming a continuous cloud, still attached at the volcano, that is being carried by strong winds south over Umnak Island and then out over the Pacific. The National Weather Service Alaska Aviation Weather Unit has issued a SIGMET warning message to aviation for the volcanic cloud up to an altitude of 34,000 ft asl.

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

Please see the National Weather Service Alaska Aviation Weather Unit web page for updated information on the volcanic cloud forecast. https://www.weather.gov/aawu/sigmets

Bogoslof volcano remains at a heightened state of unrest and in an unpredictable condition. Activity can escalate quickly with additional explosions producing high-altitude (>15,000 ft) volcanic clouds with little to no detectable precursory activity. 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 can be a lag of tens of minutes until we can characterize the magnitude of the event and the altitude of the volcanic cloud. With existing data sources, AVO may not detect low-level unrest, including explosive activity. Such low-level periods of unrest and possible explosions could pose hazards near the volcano. A Temporary Flight Restriction (TFR) remains in effect over the volcano. Please see http://tfr.faa.gov/tfr2/list.html for the status of the TFR.

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

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

Unrest at Cleveland Volcano continues. Recent data suggest that extrusion of lava in the summit crater may have slow or paused over the past week. Unrest continues. Elevated surface surface in the summit crater were observed in satellite data and vigorous steaming was seen in web camera images during periods of clear weather over the past day.

No significant activity observed in seismic and infrasound data.

Cleveland volcano is monitored with a limited real-time seismic network, which inhibits 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.

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

No significant activity has been detected in seismic and infrasound data over the past day. Satellite and web camera observations were obscured by clouds over the past day.

The level of unrest at Pavlof can change quickly and the progression to eruptive activity can occur with little or no warning. We continue to monitor Pavlof closely and will provide any new information about the status of the volcano when or if it becomes available.

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/

FOLLOW AVO ON FACEBOOK: https://facebook.com/alaska.avo

FOLLOW AVO ON TWITTER: https://twitter.com/alaska_avo

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.

---