ALASKA VOLCANO OBSERVATORY DAILY UPDATE
U.S. Geological Survey
Saturday, July 13, 2019, 12:39 PM AKDT (Saturday, July 13, 2019, 20:39 UTC)

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

Seismic tremor has continued over the last 24 hours. No eruptive activity was detected in infrasound data and cloudy conditions obscured satellite views of the volcano.

The Aviation Color Code and Volcano Alert Level were increased to YELLOW/ADVISORY at Shishaldin Volcano on Friday, July 12, 2019, based on increased seismic activity over the previous few weeks and elevated surface temperatures at the summit in satellite data. Incandescence was observed in the summit crater during a recent overflight. These observations represent a departure from normal background activity at Shishaldin, but do not necessarily indicate that an eruption will occur.

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

Seismic tremor has been continuous over the last 24 hours. No eruptive activity was detected in regional infrasound data and cloudy conditions obscured satellite views of the volcano.

Semisopochnoi is monitored with an on-island seismic network and remotely by satellite and lightning sensors. Furthermore, an infrasound array on Adak Island may detect explosive emissions from Semisopochnoi with a 13 minute delay 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

Satellite views of the volcano were cloudy over the last 24 hours, but an elevated surface temperature was visible in one image with a view of the volcano's summit. No activity was detected in regional seismic or infrasound data.

Additional episodes of lava effusion and explosions are likely and will 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.

Local seismic and infrasound data at Cleveland have been unavailable since January 26, 2019. This restricts AVO's ability to rapidly detect an explosive eruption. AVO is able to monitor the volcano for signs of eruptive activity with satellite, lightning, and regional seismic and infrasound 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

Nothing significant was observed in cloudy satellite views of the volcano over the last 24 hours. Seismicity is near or at background levels. Nothing noteworthy was detected in regional infrasound data.

Great Sitkin volcano is monitored with a local real-time seismic network, which will typically allow 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.

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, 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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