(1) VOLCANO OBSERVATORY NOTICE FOR AVIATION (VONA)
(2) Issued:	(20200401/2016Z)
(3) Volcano:	Semisopochnoi (VNUM #311060)
(4) Current Color Code:	YELLOW
(5) Previous Color Code:	ORANGE
(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:	Seismic, infrasound, and satellite data over the past two weeks have shown no signs of eruptive activity at Semisopochnoi. A robust steam plume and a crater lake have been seen in clear satellite images, but no recent ash deposits. Although seismic activity remains above background, it does not appear to be increasing towards an eruption in the short-term. Thus, AVO is reducing the Aviation Color Code to YELLOW and the Volcano Alert Level to ADVISORY. Unrest continues. Seismic activity persists and is characterized by occasional small earthquakes and satellite data show detectable volcanic gas (sulfur dioxide) being emitted from the volcano. Explosive activity could resume with little to no warning.
(12) Volcanic cloud height:	n/a
(13) Other volcanic cloud information:	n/a
(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: ADVISORY
Previous Volcano Alert Level: WATCH

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

Issued: Wednesday, April 1, 2020, 12:16 PM AKDT
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: Seismic, infrasound, and satellite data over the past two weeks have shown no signs of eruptive activity at Semisopochnoi. A robust steam plume and a crater lake have been seen in clear satellite images, but no recent ash deposits. Although seismic activity remains above background, it does not appear to be increasing towards an eruption in the short-term. Thus, AVO is reducing the Aviation Color Code to YELLOW and the Volcano Alert Level to ADVISORY. Unrest continues. Seismic activity persists and is characterized by occasional small earthquakes and satellite data show detectable volcanic gas (sulfur dioxide) being emitted from the volcano. Explosive activity could resume with little to no warning.

Recent Observations:
[Volcanic cloud height] n/a
[Other volcanic cloud information] n/a

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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