(1) VOLCANO OBSERVATORY NOTICE FOR AVIATION (VONA)
(2) Issued:	(20191207/1025Z)
(3) Volcano:	Semisopochnoi (VNUM #311060)
(4) Current Color Code:	ORANGE
(5) Previous Color Code:	YELLOW
(6) Source:	Alaska Volcano Observatory
(7) Notice Number:
(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:	An eruption signature was detected as strong tremor on local seismic and in regional infrasound networks on Adak Island. The event started at 00:26 AKST / 09:26 UTC and has continued with and ongoing but weaker local seismic signal. Any volcanic ash emissions are most likely low-level. The meteorological cloud deck has been around 10,000' (3000 m) asl over Semisopochnoi and no ash signals have been detected above this height. Nothing has been detected in lightning data.
(12) Volcanic cloud height:	No cloud observed
(13) Other volcanic cloud information:	No cloud observed
(14) Remarks:	Semisopochnoi is monitored with an on-island seismic network, and remotely by satellite and lightning sensors. An infrasound array on Adak Island could detect explosive emissions from Semisopochnoi with a 13 minute delay if atmospheric conditions permit.
(15) Contacts:	Michelle Coombs, Scientist-in-Charge, USGS mcoombs@usgs.gov (907) 786-7497 David Fee, Coordinating Scientist, UAFGI dfee1@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: Semisopochnoi (VNUM #311060)

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

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

Issued: Saturday, December 7, 2019, 1:25 AM AKST
Source: Alaska Volcano Observatory
Notice Number:
Location: N 51 deg 55 min E 179 deg 35 min
Elevation: 2625 ft (800 m)
Area: Aleutians

Volcanic Activity Summary: An eruption signature was detected as strong tremor on local seismic and in regional infrasound networks on Adak Island. The event started at 00:26 AKST / 09:26 UTC and has continued with and ongoing but weaker local seismic signal. Any volcanic ash emissions are most likely low-level.

The meteorological cloud deck has been around 10,000' (3000 m) asl over Semisopochnoi and no ash signals have been detected above this height. Nothing has been detected in lightning data.

Recent Observations:
[Volcanic cloud height] No cloud observed
[Other volcanic cloud information] No cloud observed

Remarks: Semisopochnoi is monitored with an on-island seismic network, and remotely by satellite and lightning sensors. An infrasound array on Adak Island could detect explosive emissions from Semisopochnoi with a 13 minute delay if atmospheric conditions permit.

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

David Fee, Coordinating Scientist, UAFGI
dfee1@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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