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U.S. Geological Survey
Saturday, June 24, 2017, 1:15 PM AKDT (Saturday, June 24, 2017, 21:15 UTC)

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

No volcanic unrest associated with Bogoslof has been detected in satellite, seismic or infrasound data since the series of explosive eruptive events that occurred between 16:49 AKDT, June 23 (00:49 UTC, June 24) and 00:44 AKDT, June 24 (8:44 UTC). The first event from about 16:49-16:59 AKDT June 23 generated a volcanic cloud that moved east about 250-300 miles over the North Pacific Ocean before dissipating. The volcanic cloud was no longer visible in local satellite data by about 7-8 hours after the eruption. Subsequent eruptive bursts on June 23 at 19:18-19:24 AKDT (3:18-3:24 UTC), 20:13-20:21 AKDT (4:13-4:21 UTC), 21:04-21:12 AKDT (5:04-5:12 UTC), 21:52-21:55 AKDT (5:52-5:55 UTC), and 00:40-0:44 AKDT (8:40-8:44 UTC) June 24 also produced strong seismicity and infrasound. Volcanic clouds were generated by these events but were obscured by meteorological clouds extending to 28,000 to 30,000 ft asl that had moved into the area. AVO has received no reports of ash fallout on local communities or local observations associated with this recent eruptive period.

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 is typically a lag of tens of minutes until we can characterize the magnitude of the event and the altitude of the volcanic cloud. It is possible for low-level unrest, including explosive activity, to occur that we are unable to detect with existing data sources. Such low-level periods of unrest and possible explosions could pose a hazard in the immediate vicinity of the volcano. A Temporary Flight Restriction (TFR) is in effect over the volcano at the present time. 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 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.

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

Low-level unrest is likely continuing at Cleveland Volcano, although the degree of unrest appears to be declining. Satellite and web camera views of the volcano have been obscured by clouds and fog and no unusual activity was detected in seismic or infrasound data over the past day.

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.

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 noteworthy observed in satellite images today, and no unusual activity has been detected in seismic or infrasound data over the past 24 hours. Web camera views of the volcano have been obscured by clouds and fog.

Yesterday, AVO received several pilot reports of low-level ash clouds near Pavlof Volcano at about 10,000 to 12,000 ft above sea level. Nothing unusual was apparent in seismic and infrasound data, and there were no observations of ash in satellite images at the time of the pilot reports. A high resolution satellite image of the Pavlof summit from 23 June 2017 at 01:15 UTC (17:05 AKDT, June 22) shows light steaming from the active vent and clean white unmelted snow and no sign of ash fall on the upper flanks of the volcano. Although it is possible for Pavlof to begin erupting with little to no detectable signs of unrest and minor ash emissions can occur at any time, we are unable to corroborate the reports of ash emission with available data. Over the past several days, there have been clear web camera views of the volcano that showed a persistent vapor plume extending several miles beyond the summit. Commonly these vapor plumes contain sulfur gases that can have bluish to brownish hues that may impart the appearance of ash in the plume. Because the level of unrest at Pavlof can change quickly and the progression to eruptive activity can occur with little or no warning we take note of these reports but consider it unlikely that the volcano has been erupting at a low level over the past several days. We continue to monitor Pavlof closely and will provide any new information about the status of the volcano when or if it becomes available.


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

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Dave Schneider, Acting Scientist-in-Charge, USGS
djschneider@usgs.gov (907) 786-7497

Jeff Freymueller, Coordinating Scientist, UAF
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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