(1) VOLCANO OBSERVATORY NOTICE FOR AVIATION (VONA)
(2) Issued: (20170213/1900Z)
(3) Volcano: Bogoslof (VNUM #311300)
(4) Current Color Code: ORANGE
(5) Previous Color Code: RED
(6) Source: Alaska Volcano Observatory
(7) Notice Number:
(8) Volcano Location: N 53 deg 55 min W 168 deg 2 min
(9) Area: Aleutians
(10) Summit Elevation: 492 ft (150 m)
(11) Volcanic Activity Summary: Strong seismic activity at Bogoslof this morning from about 16:24 to 17:32 UTC (07:24 to 08:32 AKST) was detected on stations from nearby islands. Similar seismic activity has been associated with explosive eruptions that produced significant ash clouds from the volcano. Thus, AVO raised the Aviation Color Code to RED and Alert level to WARNING for Bogoslof volcano.

However, satellite data through 18:30 UTC (09:30 AKST) show no volcanic cloud visible about the weather cloud tops of about 10,000 ft asl. There were also no lightning strokes detected during this morning's activity. We therefore conclude that, despite the intensity of seismic activity, a significant volcanic cloud was not produced during this event. We are thus lowering the Aviation Color Code to ORANGE and the Alert Level to WATCH.

Ash emissions to lower altitudes, as well as other eruptive activity, likely did occur during this morning's event, and conditions at the volcano remain unstable. Additional explosive activity could occur at any time, with little or no advance warning.
(12) Volcanic cloud height: No cloud above about 10,000 ft asl
(13) Other volcanic cloud information: None available
(14) Remarks: The SIGMET warning message for aviation, issued by the National Weather Service Alaska Aviation Weather Unit, was cancelled earlier this morning. Status of the ash cloud forecast can be found at their website at http://aawu.arh.noaa.gov/

The National Weather Service issued a Marine Weather Statement for the area around Umnak Pass: http://www.weather.gov/afc/
(15) Contacts: Michelle Coombs, Scientist-in-Charge, USGS
mcoombs@usgs.gov (907) 786-7497

Jessica Larsen, Acting Coordinating Scientist, UAFGI
jflarsen@alaska.edu (907) 322-4085
(16) Next Notice:

AVO/USGS Volcanic Activity Notice

Volcano: Bogoslof (VNUM #311300)

Current Volcano Alert Level: WATCH
Previous Volcano Alert Level: WARNING

Current Aviation Color Code: ORANGE
Previous Aviation Color Code: RED

Issued: Monday, February 13, 2017, 10:00 AM AKST
Source: Alaska Volcano Observatory
Notice Number:
Location: N 53 deg 55 min W 168 deg 2 min
Elevation: 492 ft (150 m)
Area: Aleutians

Volcanic Activity Summary: Strong seismic activity at Bogoslof this morning from about 16:24 to 17:32 UTC (07:24 to 08:32 AKST) was detected on stations from nearby islands. Similar seismic activity has been associated with explosive eruptions that produced significant ash clouds from the volcano. Thus, AVO raised the Aviation Color Code to RED and Alert level to WARNING for Bogoslof volcano.

However, satellite data through 18:30 UTC (09:30 AKST) show no volcanic cloud visible about the weather cloud tops of about 10,000 ft asl. There were also no lightning strokes detected during this morning's activity. We therefore conclude that, despite the intensity of seismic activity, a significant volcanic cloud was not produced during this event. We are thus lowering the Aviation Color Code to ORANGE and the Alert Level to WATCH.

Ash emissions to lower altitudes, as well as other eruptive activity, likely did occur during this morning's event, and conditions at the volcano remain unstable. Additional explosive activity could occur at any time, with little or no advance warning.


Recent Observations:
[Volcanic cloud height] No cloud above about 10,000 ft asl
[Other volcanic cloud information] None available

Remarks: The SIGMET warning message for aviation, issued by the National Weather Service Alaska Aviation Weather Unit, was cancelled earlier this morning. Status of the ash cloud forecast can be found at their website at http://aawu.arh.noaa.gov/

The National Weather Service issued a Marine Weather Statement for the area around Umnak Pass: http://www.weather.gov/afc/

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

Jessica Larsen, Acting Coordinating Scientist, UAFGI
jflarsen@alaska.edu (907) 322-4085

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.