AVO/USGS Volcanic Activity Notice

Volcano: Semisopochnoi (VNUM #311060)

Current Volcano Alert Level: WATCH
Previous Volcano Alert Level: ADVISORY

Current Aviation Color Code: ORANGE
Previous Aviation Color Code: YELLOW


Issued: Sunday, August 21, 2022, 3:01 PM AKDT
Source: Alaska Volcano Observatory
Notice Number: 2022/A927
Location: N 51 deg 55 min E 179 deg 35 min
Elevation: 2625 ft (800 m)
Area: Aleutians

Volcanic Activity Summary:

A short-lived explosion occured at 1:47 PM AKDT (21:47 UTC) today that produced ash emissions observed in local webcams. Ash emissions ceased by 2:16 PM AKDT (22:16 UTC). The ash plume was not visible above the meteorological clouds in satellite images, thus was below 20,000 ft. (6 km) above sea level. This event is similar to eruptive activity observed over the last year at Semisopochnoi, but not since June 12. The Aviation Color Code and Volcano Alert Level are being raised to ORANGE/WATCH.

Small eruptions producing minor ash deposits within the vicinity of the active north crater of Mount Cerberus and ash clouds usually under 10,000 ft (3 km) above sea level have characterized the recent activity and more ash-producing events could occur again with little warning. 

Recent Observations:
[Volcanic cloud height] less than 20,000 ft. above sea level
[Other volcanic cloud information] none
[Ballistics] none
[Lava flow/dome] none
[Lava flow] none

Hazard Analysis:
[General hazards] Explosive activity and ash emissions at Semisopochnoi could increase again at any time.

Remarks:

Semisopochnoi is monitored by a local seismic and infrasound network, local web cameras, regional lightning and infrasound sensors, and satellite data.

Contacts:

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

David Fee, Coordinating Scientist, UAFGI, dfee1@alaska.edu, (907) 378-5460

Next Notice:

A new VAN will be issued if conditions change significantly or alert levels are modified. While a VAN is in effect, regularly scheduled updates are posted at http://www.avo.alaska.edu

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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(1) VOLCANO OBSERVATORY NOTICE FOR AVIATION (VONA)
(2) Issued:	(20220821/2301Z)
(3) Volcano:	Semisopochnoi (VNUM #311060)
(4) Current Color Code:	ORANGE
(5) Previous Color Code:	YELLOW
(6) Source:	Alaska Volcano Observatory
(7) Notice Number:	2022/A927
(8) Volcano Location:	N 51 deg 55 min E 179 deg 35 min
(9) Area:	Aleutians
(10) Summit Elevation:	2625 ft (800 m)
(11) Volcanic Activity Summary:	A short-lived explosion occured at 1:47 PM AKDT (21:47 UTC) today that produced ash emissions observed in local webcams. Ash emissions ceased by 2:16 PM AKDT (22:16 UTC). The ash plume was not visible above the meteorological clouds in satellite images, thus was below 20,000 ft. (6 km) above sea level. This event is similar to eruptive activity observed over the last year at Semisopochnoi, but not since June 12. The Aviation Color Code and Volcano Alert Level are being raised to ORANGE/WATCH. Small eruptions producing minor ash deposits within the vicinity of the active north crater of Mount Cerberus and ash clouds usually under 10,000 ft (3 km) above sea level have characterized the recent activity and more ash-producing events could occur again with little warning.
(12) Volcanic cloud height:	less than 20,000 ft. above sea level
(13) Other volcanic cloud information:	none
(14) Remarks:	Semisopochnoi is monitored by a local seismic and infrasound network, local web cameras, regional lightning and infrasound sensors, and satellite data.
(15) Contacts:	Michelle Coombs, Scientist-in-Charge, USGS, mcoombs@usgs.gov, (907) 786-7497 David Fee, Coordinating Scientist, UAFGI, dfee1@alaska.edu, (907) 378-5460
(16) Next Notice:	A new VAN will be issued if conditions change significantly or alert levels are modified. While a VAN is in effect, regularly scheduled updates are posted at http://www.avo.alaska.edu

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