(1) VOLCANO OBSERVATORY NOTICE FOR AVIATION (VONA)
(2) Issued:	(20191212/1718Z)
(3) Volcano:	Shishaldin (VNUM #311360)
(4) Current Color Code:	ORANGE
(5) Previous Color Code:	ORANGE
(6) Source:	Alaska Volcano Observatory
(7) Notice Number:
(8) Volcano Location:	N 54 deg 45 min W 163 deg 58 min
(9) Area:	Aleutians
(10) Summit Elevation:	9373 ft (2857 m)
(11) Volcanic Activity Summary:	A short-lived explosion from Shishaldin Volcano has produced an ash cloud to 20,000 - 25,000 feet and is moving to the W-NW. A tremor burst was observed in seismic data at 7:10 (16:10 UTC) and had a duration of about 3 minutes. Three lightning stroke were detected. Shishaldin remains at Aviation Color Code ORANGE and Alert Level WATCH. The National Weather Service has issued SIGMET to 25,000 ft above sea level (https://www.weather.gov/aawu/). Shishadin remains at a heightened level of unrest and explosions may occur with little warning. Shishaldin is monitored by local seismic and infrasound sensors, satellite data, a web camera, a telemetered geodetic network, and distant infrasound and lightning networks.
(12) Volcanic cloud height:	25,000
(13) Other volcanic cloud information:	Rising above cloud deck moving to the W-NW from Shishaldin at approximately 45 knots
(14) Remarks:	Shishaldin volcano, located near the center of Unimak Island in the eastern Aleutian Islands, is a spectacular symmetric cone with a base diameter of approximately 16 km (10 mi). A 200-m-wide (660 ft) funnel-shaped summit crater typically emits a steam plume and occasional small amounts of ash. Shishaldin is one of the most active volcanoes in the Aleutian volcanic arc, with at least 54 episodes of unrest including over 24 confirmed eruptions since 1775. Most eruptions are relatively small, although the April-May 1999 event generated an ash column that reached 45,000 ft above sea level.
(15) Contacts:	Kristi Wallace, Acting Scientist-in-Charge, USGS kwallace@usgs.gov (907) 786-7497 Janet Schaefer, Acting Coordinating Scientist, UAFGI janet.schaefer@alaska.gov (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: Shishaldin (VNUM #311360)

Current Volcano Alert Level: WATCH

Current Aviation Color Code: ORANGE

Issued: Thursday, December 12, 2019, 8:18 AM AKST
Source: Alaska Volcano Observatory
Notice Number:
Location: N 54 deg 45 min W 163 deg 58 min
Elevation: 9373 ft (2857 m)
Area: Aleutians

Volcanic Activity Summary: A short-lived explosion from Shishaldin Volcano has produced an ash cloud to 20,000 - 25,000 feet and is moving to the W-NW. A tremor burst was observed in seismic data at 7:10 (16:10 UTC) and had a duration of about 3 minutes. Three lightning stroke were detected. Shishaldin remains at Aviation Color Code ORANGE and Alert Level WATCH. The National Weather Service has issued SIGMET to 25,000 ft above sea level (https://www.weather.gov/aawu/).

Shishadin remains at a heightened level of unrest and explosions may occur with little warning.

Shishaldin is monitored by local seismic and infrasound sensors, satellite data, a web camera, a telemetered geodetic network, and distant infrasound and lightning networks.

Recent Observations:
[Volcanic cloud height] 25,000
[Other volcanic cloud information] Rising above cloud deck moving to the W-NW from Shishaldin at approximately 45 knots

Remarks: Shishaldin volcano, located near the center of Unimak Island in the eastern Aleutian Islands, is a spectacular symmetric cone with a base diameter of approximately 16 km (10 mi). A 200-m-wide (660 ft) funnel-shaped summit crater typically emits a steam plume and occasional small amounts of ash. Shishaldin is one of the most active volcanoes in the Aleutian volcanic arc, with at least 54 episodes of unrest including over 24 confirmed eruptions since 1775. Most eruptions are relatively small, although the April-May 1999 event generated an ash column that reached 45,000 ft above sea level.

Contacts: Kristi Wallace, Acting Scientist-in-Charge, USGS
kwallace@usgs.gov (907) 786-7497

Janet Schaefer, Acting Coordinating Scientist, UAFGI
janet.schaefer@alaska.gov (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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