ALASKA VOLCANO OBSERVATORY DAILY UPDATE
U.S. Geological Survey
Wednesday, July 22, 2020, 12:06 PM AKDT (Wednesday, July 22, 2020, 20:06 UTC)

MAKUSHIN VOLCANO (VNUM #311310)
53°53'24" N 166°55'30" W, Summit Elevation 5906 ft (1800 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW

A sequence of small earthquakes centered southeast of the summit that began on June 15 is continuing. No activity was observed in cloudy satellite and web camera imagery over the past day.

The earthquake sequence may be associated with volcanic unrest, but there have been no signs of deformation or surface activity noted in other monitoring data. It is likely that we would see additional signs of unrest prior to an eruption, should it occur. The volcano is monitored with a network of seismic and GPS instruments, a web camera, satellite data, and regional infrasound and lightning detection instruments.

If an eruption were to occur, the main hazard would likely be from airborne ash and ash fall. Wind trajectory plots and hypothetical ash fall model information is available at https://www.avo.alaska.edu/activity/Makushin.php These models are updated twice per day in a hypothetical mode and will be updated immediately if there is an eruption. Seismic data, web camera images, and information products are also available at this site.

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 activity was observed in cloudy satellite and partly clear web camera imagery over the past day. No activity was detected on local or regional geophysical networks over the past day.

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 the network is operational, Cleveland volcano is monitored by only two seismic stations, which restricts 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.

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

Unrest continues at Great Sitkin. Small local earthquakes have occurred at the volcano over the past day. No explosive activity was detected by regional infrasound sensors. No activity was observed in cloudy satellite and web camera imagery of the volcano.

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

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

Low-level unrest continues at Semisopochnoi. Seismicity at the volcano remains above background with occasional small earthquakes occurring over the past day. No eruptive activity was observed in cloudy satellite imagery or detected by regional infrasound sensors.

Semisopochnoi is monitored by local seismic sensors, satellite data, and 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.

VENIAMINOF VOLCANO (VNUM #312070)
56°11'52" N 159°23'35" W, Summit Elevation 8225 ft (2507 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW

Low-level seismic unrest continues at Veniaminof. Local seismicity has been obscured by the magnitude 7.8 tectonic earthquake and its aftershocks that occurred July 21 at 10:12 PM AKDT (July 22, 06:12 UTC). No explosive activity was detected by regional infrasound sensors. Weak elevated surface temperatures were observed in satellite data and no unusual activity was observed in clear web camera imagery.

Veniaminof volcano is monitored with a local real-time seismic network, which will typically allows AVO to detect changes in unrest that may lead to a more significant explosive eruption. AVO combines seismic, infrasound, lightning, and satellite data for rapid detection of such events.

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

Pavel Izbekov, Acting Coordinating Scientist, UAFGI
peizbekov@alaska.gov (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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