ALASKA VOLCANO OBSERVATORY DAILY UPDATE
U.S. Geological Survey
Wednesday, June 9, 2021, 12:38 PM AKDT (Wednesday, June 9, 2021, 20:38 UTC)

SEMISOPOCHNOI VOLCANO (VNUM #311060)
51°55'44" N 179°35'52" E, Summit Elevation 2625 ft (800 m)
Current Volcano Alert Level: WATCH
Current Aviation Color Code: ORANGE

Volcanic activity at the north crater of Mount Cerberus remains at a low levels over the past day. Nothing significant has been observed in seismic or regional infrasound data. Elevated surface temperatures and a robust steam plume were observed in satellite data. Overall the volcano is restless but activity has remained low.

AVO field crews successfully completed upgrades to the monitoring network yesterday.

Small eruptions producing minor ash deposits within the vicinity of the active north crater of Mount Cerberus and ash clouds under 10,000 ft above sea level are typical of recent activity at Semisopochnoi. Small explosions may occur without warning and could be undetected by regional infrasound sensors and cloudy weather conditions.

Semisopochnoi is monitored by a local seismic network, satellite data, regional infrasound, and lightning detection instruments. An infrasound array on Adak Island may detect explosive emissions from Semisopochnoi with a slight delay (approximately 13 minutes) if atmospheric conditions permit.

CLEVELAND VOLCANO (VNUM #311240)
52°49'20" N 169°56'42" W, Summit Elevation 5676 ft (1730 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW

No significant activity was observed in seismic or infrasound data over the past day. Elevated surface temperatures were observed in satellite data in the vicinity of the active summit vent area.

Episodes of lava effusion and explosions can occur without advance warning. Explosions from Cleveland are normally short duration and only present a hazard to aviation in the immediate vicinity of the volcano. Larger explosions that present a more widespread hazard to aviation are possible, but are less likely and occur less frequently.

When operational, Cleveland volcano is monitored by only two seismic stations, which restricts AVO's ability to precisely locate earthquakes and 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.

GREAT SITKIN VOLCANO (VNUM #311120)
52°4'35" N 176°6'39" W, Summit Elevation 5709 ft (1740 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW

Seismicity has remained at low levels over the past day. Slightly elevated surface temperatures were observed in satellite data and nothing unusual was seen in partly cloudy webcam views.

The prognosis for renewed eruptive activity is uncertain, although the ongoing quiescence is suggestive of a gradual return to normal background conditions. It remains possible for the level of unrest at the volcano to change quickly, and if so, additional explosive events could occur in the coming days, weeks or months. AVO is monitoring the volcano closely and will report on significant changes and observations in monitoring data should they occur.

Great Sitkin volcano is monitored by local seismic and infrasound sensors, satellite data, web cameras, and remote infrasound and lightning networks.

GARELOI VOLCANO (VNUM #311070)
51°47'21" N 178°47'46" W, Summit Elevation 5161 ft (1573 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW

Elevated seismicity continues over the past day. There have been no other notable changes at the volcano in partly cloudy satellite data or web camera views.

Gareloi volcano persistently emits magmatic gases from a fumarole field on the south crater and commonly exhibits low-level seismic activity. These observations suggest the presence of shallow magma and potential interaction with a hydrothermal system. The current increase in seismicity likely reflects a change to the magmatic-hydrothermal system, but it is not clear that the likelihood of a volcanic eruption has increased. AVO will continue to monitor activity to determine if the recent changes are related to influx of new magma or other changes to the magma system.

Gareloi is monitored by a local seismic and infrasound network, satellite data, and regional infrasound and lightning-detection networks.

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:

Michelle Coombs, Scientist-in-Charge, USGS mcoombs@usgs.gov (907) 786-7497

David Fee, Coordinating Scientist, UAF 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.

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