(1) VOLCANO OBSERVATORY NOTICE FOR AVIATION (VONA)
(2) Issued: (20181026/0535Z)
(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: Strong seismic tremor from Semisopochnoi consistent with an eruption began at 4:47 UTC (20:47 AKDT) and is currently diminishing. Satellite data through 5:00 UTC (21:00 AKDT) show a small ash cloud at about 12,000 ft asl.

AVO is raising the Aviation Color Code and Alert Level to Orange/Watch for Semisopochnoi.
(12) Volcanic cloud height: about 12,000 ft asl
(13) Other volcanic cloud information: winds toward the southeast
(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: WATCH
Previous Volcano Alert Level: ADVISORY

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

Issued: Thursday, October 25, 2018, 9:35 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: Strong seismic tremor from Semisopochnoi consistent with an eruption began at 4:47 UTC (20:47 AKDT) and is currently diminishing. Satellite data through 5:00 UTC (21:00 AKDT) show a small ash cloud at about 12,000 ft asl.

AVO is raising the Aviation Color Code and Alert Level to Orange/Watch for Semisopochnoi.


Recent Observations:
[Volcanic cloud height] about 12,000 ft asl
[Other volcanic cloud information] winds toward the southeast

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.