ALASKA VOLCANO OBSERVATORY DAILY UPDATE
U.S. Geological Survey
Thursday, March 12, 2020, 1:24 PM AKDT (Thursday, March 12, 2020, 21:24 UTC)

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

Small local earthquakes continued over the past day. Clear satellite and web camera images showed no sign of activity.

Great Sitkin volcano is monitored with a local real-time seismic network, which will typically allows AVO to detect changes in unrest that may lead to an explosive eruption. Rapid detection of an ash-producing eruption would be accomplished using a combination of seismic, infrasound, lightning, and satellite data.

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

Intermittent tremor bursts continued until yesterday afternoon. Some of these tremor bursts were accompanied by very weak infrasound detections suggesting possible weak surface activity. Clear satellite images, however, showed no indication of eruptive activity. Overnight, seismicity was relatively quiet.

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

Seismicity remains low. Satellite image indicated slightly elevated, but not unusual, surface temperatures at the vent. No steaming was evident in clear web camera views but higher resolution satellite images showed typical steaming within the crater.

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.

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.

SHISHALDIN VOLCANO (VNUM #311360)
54°45'19" N 163°58'16" W, Summit Elevation 9373 ft (2857 m)
Current Volcano Alert Level: ADVISORY
Current Aviation Color Code: YELLOW

Slightly elevated seismicity was detected over the last day. Satellite images indicated weakly elevated surface temperatures from within the summit vent. Steaming from the summit was visible in clear web camera and high resolution satellite images. A very minor ash deposit was visible on the upper flanks, but this could be from ash resuspension or a minor collapse event at the summit.

Shishaldin is monitored by local seismic and infrasound sensors, satellite data, web cameras, a telemetered geodetic network, and distant infrasound and lightning 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:

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

David Fee, Coordinating Scientist, UAFGI
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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