(1) VOLCANO OBSERVATORY NOTICE FOR AVIATION (VONA)
(2) Issued:	(20210115/2134Z)
(3) Volcano:	Shishaldin (VNUM #311360)
(4) Current Color Code:	UNASSIGNED
(5) Previous Color Code:	GREEN
(6) Source:	Alaska Volcano Observatory
(7) Notice Number:	2021/A4
(8) Volcano Location:	N 54 deg 45 min W 163 deg 58 min
(9) Area:	Aleutians
(10) Summit Elevation:	9373 ft (2857 m)
(11) Volcanic Activity Summary:	The Shishaldin network has several outages affecting GPS, seismic, and infrasound stations. Due to the impaired local monitoring stations, the Alaska Volcano Observatory is changing the Aviation Color Code and the Volcano Alert Level UNASSIGNED/UNASSIGNED. This most recent eruptive cycle at Shishaldin began in July 2019 with pauses in activity in late September/early October 2019 and February 2020. The most recent activity in mid-March was confined to the summit crater except for minor ash deposits near the summit. Only minor rockfalls within the summit crater, not associated with eruptive activity, have been detected since early April. Pauses in eruptions are common at Shishaldin, and therefore eruptive activity could resume with little warning. The Alaska Volcano Observatory will continue to monitor the volcano closely. The Alaska Volcano Observatory continues to monitor Shishaldin with the local web camera imagery, satellite data and remote infrasound, seismic and lightning networks.
(12) Volcanic cloud height:	na
(13) Other volcanic cloud information:	na
(14) Remarks:	Shishaldin volcano, located near the center of Unimak Island in the eastern Aleutian Islands, is a spectacular symmetric cone with a base diameter of approximately 16 km (10 mi). A 200-m-wide (660 ft) funnel-shaped summit crater typically emits a steam plume and occasional small amounts of ash. Shishaldin is one of the most active volcanoes in the Aleutian volcanic arc, with at least 54 episodes of unrest including over 24 confirmed eruptions since 1775. Most eruptions are relatively small, although the April-May 1999 event generated an ash column that reached 45,000 ft above sea level.
(15) Contacts:	Matt Haney, Acting Scientist-in-Charge, USGS mhaney@usgs.gov (907) 786-7497 Taryn Lopez, Acting Coordinating Scientist, UAF tmlopez@alaska.edu (907) 322-4085
(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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AVO/USGS Volcanic Activity Notice

Volcano: Shishaldin (VNUM #311360)

Current Volcano Alert Level: UNASSIGNED
Previous Volcano Alert Level: NORMAL

Current Aviation Color Code: UNASSIGNED
Previous Aviation Color Code: GREEN

Issued: Friday, January 15, 2021, 12:34 PM AKST
Source: Alaska Volcano Observatory
Notice Number: 2021/A4
Location: N 54 deg 45 min W 163 deg 58 min
Elevation: 9373 ft (2857 m)
Area: Aleutians

Volcanic Activity Summary: The Shishaldin network has several outages affecting GPS, seismic, and infrasound stations. Due to the impaired local monitoring stations, the Alaska Volcano Observatory is changing the Aviation Color Code and the Volcano Alert Level UNASSIGNED/UNASSIGNED.

This most recent eruptive cycle at Shishaldin began in July 2019 with pauses in activity in late September/early October 2019 and February 2020. The most recent activity in mid-March was confined to the summit crater except for minor ash deposits near the summit. Only minor rockfalls within the summit crater, not associated with eruptive activity, have been detected since early April. Pauses in eruptions are common at Shishaldin, and therefore eruptive activity could resume with little warning. The Alaska Volcano Observatory will continue to monitor the volcano closely.

The Alaska Volcano Observatory continues to monitor Shishaldin with the local web camera imagery, satellite data and remote infrasound, seismic and lightning networks.

Recent Observations:
[Volcanic cloud height] na
[Other volcanic cloud information] na

Remarks: Shishaldin volcano, located near the center of Unimak Island in the eastern Aleutian Islands, is a spectacular symmetric cone with a base diameter of approximately 16 km (10 mi). A 200-m-wide (660 ft) funnel-shaped summit crater typically emits a steam plume and occasional small amounts of ash. Shishaldin is one of the most active volcanoes in the Aleutian volcanic arc, with at least 54 episodes of unrest including over 24 confirmed eruptions since 1775. Most eruptions are relatively small, although the April-May 1999 event generated an ash column that reached 45,000 ft above sea level.

Contacts: Matt Haney, Acting Scientist-in-Charge, USGS
mhaney@usgs.gov (907) 786-7497

Taryn Lopez, Acting Coordinating Scientist, UAF
tmlopez@alaska.edu (907) 322-4085

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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