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(1) VOLCANO OBSERVATORY NOTICE FOR AVIATION (VONA)
(2) Issued: (20200109/2325Z)
(3) Volcano: Semisopochnoi (VNUM #311060)
(4) Current Color Code: YELLOW
(5) Previous Color Code: ORANGE
(6) Source: Alaska Volcano Observatory
(7) Notice Number: 2020/A17
(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: There has been no explosive activity observed at Semisopochnoi since December 19, 2019. Seismic tremor had decreased over the subsequent weeks with the last observation of seismic tremor on December 29, 2019. Seismicity has continued to decline, but remains above background. Thus, the Aviation Color Code is lowered to YELLOW and the Alert Level to ADVISORY.
(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

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: Thursday, January 9, 2020, 2:25 PM AKST
Source: Alaska Volcano Observatory
Notice Number: 2020/A17
Location: N 51 deg 55 min E 179 deg 35 min
Elevation: 2625 ft (800 m)
Area: Aleutians

Volcanic Activity Summary: There has been no explosive activity observed at Semisopochnoi since December 19, 2019. Seismic tremor had decreased over the subsequent weeks with the last observation of seismic tremor on December 29, 2019. Seismicity has continued to decline, but remains above background. Thus, the Aviation Color Code is lowered to YELLOW and the Alert Level to ADVISORY.

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.