ALASKA VOLCANO OBSERVATORY DAILY UPDATE
U.S. Geological Survey
Thursday, June 1, 2017, 11:55 AM AKDT (Thursday, June 1, 2017, 19:55 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

Unrest continues at Bogoslof volcano. A short duration (less than 10 minute-long) explosion beginning at 2:42 UTC on June 1 (18:42 AKDT on May 31) was detected in seismic and infrasound data and produced a small volcanic cloud that was observed in satellite images. The cloud rose to an altitude of about 24,000 ft asl and was transported to the WNW over the Bering Sea and where it dissipated. There was no lightning detected during this small explosion and no new ash emissions have been detected since that time. The explosion was preceded by a several hour-long swarm of very small earthquakes. Seismicity decreased in the hours prior to the explosion and has remained below our detection threshold using data from instruments located on nearby islands. Based on the brevity of the explosion and the low-level of detectable seismicity the Aviation Color Code remains at Orange and the Volcano Alert Level at Watch.

Bogoslof volcano remains at a heightened state of unrest and in an unpredictable condition. Activity may ramp back up with additional explosions producing high-altitude (>15,000 ft) volcanic clouds with little 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.

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

Vigorous steaming from the summit crater was observed in web camera images during periods of clear weather over the past day. No significant activity was observed in cloudy satellite images and no activity was detected in seismic or infrasound data during 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.

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/

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CONTACT INFORMATION:

Matt Haney, Acting Scientist-in-Charge, USGS
mhaney@usgs.gov (907) 786-7497

Jessica Larsen, Acting Coordinating Scientist, UAF
jflarsen@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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