(1) VOLCANO OBSERVATORY NOTICE FOR AVIATION (VONA)
(2) Issued:	(20150528/2152Z)
(3) Volcano:	Semisopochnoi (VNUM #311060)
(4) Current Color Code:	UNASSIGNED
(5) Previous Color Code:	YELLOW
(6) Source:	Alaska Volcano Observatory
(7) Notice Number:	2015/A3
(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 decline in seismicity over the last few months and no sign of activity in daily satellite images prompts AVO to downgrade Semisopochnoi volcano from Aviation Color Code YELLOW and Volcanic Alert Level ADVISORY to UNASSIGNED. Following a brief seismic swarm in June and July, 2014, an increase in seismicity at Semisopochnoi seismic stations was recorded in January 2015. Numerous small earthquakes, most with magnitudes less than 1 over the next several months led AVO to include Semisopochnoi in the March 20, 2015 Weekly Update. On March 25, 2015, citing increased earthquake activity including brief periods of tremor, AVO raised the Aviation Color Code and Volcano Alert Level to YELLOW/ADVISORY. Over the next two months seismic levels have declined and no activity has been observed in daily satellite images or other remote sensing data. AVO will continue to monitor Semisopochnoi seismic data and evaluate daily satellite images.
(12) Volcanic cloud height:	Unknown
(13) Other volcanic cloud information:	Unknown
(14) Remarks:
(15) Contacts:	Chris Waythomas, Acting Scientist-in-Charge, USGS chris@usgs.gov (907) 786-7497 Jeff Freymueller, Coordinating Scientist, UAFGI jeff.freymueller@gi.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: UNASSIGNED
Previous Volcano Alert Level: ADVISORY

Current Aviation Color Code: UNASSIGNED
Previous Aviation Color Code: YELLOW

Issued: Thursday, May 28, 2015, 1:52 PM AKDT
Source: Alaska Volcano Observatory
Notice Number: 2015/A3
Location: N 51 deg 55 min E 179 deg 35 min
Elevation: 2625 ft (800 m)
Area: Aleutians

Volcanic Activity Summary: A decline in seismicity over the last few months and no sign of activity in daily satellite images prompts AVO to downgrade Semisopochnoi volcano from Aviation Color Code YELLOW and Volcanic Alert Level ADVISORY to UNASSIGNED.

Following a brief seismic swarm in June and July, 2014, an increase in seismicity at Semisopochnoi seismic stations was recorded in January 2015. Numerous small earthquakes, most with magnitudes less than 1 over the next several months led AVO to include Semisopochnoi in the March 20, 2015 Weekly Update. On March 25, 2015, citing increased earthquake activity including brief periods of tremor, AVO raised the Aviation Color Code and Volcano Alert Level to YELLOW/ADVISORY. Over the next two months seismic levels have declined and no activity has been observed in daily satellite images or other remote sensing data.

AVO will continue to monitor Semisopochnoi seismic data and evaluate daily satellite images.

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

Contacts: Chris Waythomas, Acting Scientist-in-Charge, USGS
chris@usgs.gov (907) 786-7497

Jeff Freymueller, Coordinating Scientist, UAFGI
jeff.freymueller@gi.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

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