ALASKA VOLCANO OBSERVATORY DAILY UPDATE U.S. Geological Survey Wednesday, May 17, 2017, 2:03 PM AKDT (Wednesday, May 17, 2017, 22:03 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
An increase in seismicity at Bogoslof was detected last night at 22:32 AKDT (06:32 UTC 05/17/2017) at stations on Unalaska and Umnak Islands. As a result, AVO increased the Aviation Color Code/Alert Level to ORANGE/WATCH. Immediately thereafter, pilot reports of an ash cloud to 36,000 feet above sea level, prompted a increase in the Aviation Color Code/Alert Level to RED/WARNING. The increase in seismic energy lasted 73 minutes. The eruption triggered 56 lightning detections and infrasound signals were detected on Umnak Island and Dillingham. The resulting plume drifted to the southwest and was observed in satellite imagery. Trace ashfall was reported and confirmed in the community of Nikolski on Umnak Island. Following the eruption, seismic amplitudes decreased significantly. As a result, AVO decreased the Aviation Color Code/Alert Level to ORANGE/WATCH earlier today.
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
A short-lived explosion was detected in seismic and infrasound data last night at Cleveland volcano at 19:38 AKDT (03:38 UTC 05/17/2017). The increase in seismicity lasted about 10 minutes. The ash cloud was observed in satellite data drifting to the southwest for approximately 5 hours. The dome at the summit of the volcano that was emplaced in April-May, 2017 has been completely removed by this explosion.
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
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Pavel Izbekov, Acting Coordinating Scientist, UAFGI
pavel@gi.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.