USGS Volcano Notice for Aviation - DOI-USGS-AVO-2023-08-15T03:11:31-08:00

(1) VOLCANO OBSERVATORY NOTICE FOR AVIATION (VONA)
(2) Issued:	(20230815/1135Z)
(3) Volcano:	Shishaldin (VNUM #311360)
(4) Current Color Code:	ORANGE
(5) Previous Color Code:	ORANGE
(6) Source:	Alaska Volcano Observatory
(7) Notice Number:	2023/A1266
(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:	Explosive eruptive activity is occurring at Shishaldin Volcano. A low-level ash cloud to about 25,000 ft (7.6 km) above sea level and moving northeast is evident in satellite data. This follows a several-hour increase in seismic tremor. Explosion signals have been detected in infrasound data since at least 2:00 AKDT (10:00 UTC) and the National Weather Service has detected lightning in the vicinity of the volcano. A SIGMET for this ash cloud has been issued. Based on previous eruption cycles, significant ash emissions are likely to continue for the next few hours. Pyroclastic and mudflows are likely on the immediate flanks of the volcano. Shishaldin Volcano is monitored by local seismic and infrasound sensors, web cameras, and a telemetered geodetic network. In addition to the local monitoring network, AVO uses nearby geophysical networks, regional infrasound and lighting data, and satellite images to detect eruptions.
(12) Volcanic cloud height:	drifting below 25,000 ft (7.6 km) above sea level, see SIGMET. Emissions from the vent are likely occurring at low levels.
(13) Other volcanic cloud information:	Unknown
(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 10 miles (16 km). A 660 ft. (200 m) wide 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 26 confirmed eruptions since 1824. Most eruptions are relatively small, although the April-May 1999 event generated an ash column that reached 45,000 ft. (14 km) above sea level.
(15) Contacts:	Matt Haney, Scientist-in-Charge, USGS mhaney@usgs.gov (907) 786-7497 David Fee, Coordinating Scientist, UAFGI dfee1@alaska.edu (907) 378-5460
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