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AVO VOLCANO ACTIVITY NOTIFICATION

ALASKA VOLCANO OBSERVATORY DAILY UPDATE
U.S. Geological Survey
Tuesday, March 23, 2021, 12:53 PM AKDT (Tuesday, March 23, 2021, 20:53 UTC)


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

Low-level eruptive activity continues at Veniaminof. Seismic tremor continues and airwaves from small explosions have been observed in local seismic data and distant Infrasound networks over the past day. Minor ash emissions from the small cone within the summit caldera continue and was reported by a pilot this morning rising up to 10,000 asl. These ash emissions are visible in satellite images this morning. A plume of sulfur dioxide gas associated with the ash emissions and lava eruption were observed in satellite data yesterday afternoon. The FAA web camera in Perryville, which provides observations of the volcano during clear weather, has been offline for the past 25 hours. Highly elevated surface temperatures were observed in satellite data over the past day indicating that the eruption of lava at a vent ~1 km (0.6 miles) east of the summit cone continues. Satellite radar data, which can observe the surface through clouds, shows expansion in the area of subsidence of the glacial ice over the flank vent from which the lava is being erupted.

Eruptive activity at Veniaminof usually consists of minor ash emissions, lava fountaining and lava flows from the small cone in the summit caldera. Ash emissions are typically confined to the summit crater, but larger events can result in ash fall in nearby communities and drifting airborne ash.

The partial restoration of local seismic data will help the Alaska Volcano Observatory to detect changes in unrest that may lead to a more significant explosive eruption. AVO combines seismic, infrasound, lightning, web camera, and satellite data for rapid detection of such events.


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

Unrest continues. Three explosions were detected in regional infrasound sensors over the past day. High cloud cover (~30,000 ft) obscured the volcano during these explosions but no ash was observed rising above the meteorological cloud deck. A plume of sulfur dioxide (a common volcanic gas) was observed in satellite data yesterday afternoon, further indicating continued unrest.

Semisopochnoi is monitored by 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 activity has been observed in seismic or infrasound data in the past 24 hours. Weather clouds are obscuring the volcano in satellite data.

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.


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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CONTACT INFORMATION:

Matthew Haney, Acting Scientist-in-Charge, USGS
mhaney@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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Page modified: December 2, 2016 10:12
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