|(1) VOLCANO OBSERVATORY NOTICE FOR AVIATION (VONA)|
|(3) Volcano:||Shishaldin (VNUM #311360)|
|(4) Current Color Code:||YELLOW|
|(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|
|(10) Summit Elevation:||9373 ft (2857 m)|
|(11) Volcanic Activity Summary:||Seismicity at Shishaldin Volcano has decreased over the past two weeks to levels slightly above background. Similarly, satellite views show no lava or changes within the crater since the start of April, accompanied by a decrease in surface temperatures. Eruptive activity therefore appears to have ended or paused. Due to this decrease in activity, the Alaska Volcano Observatory is decreasing the Aviation Color Code for Shishaldin Volcano to YELLOW and the Alert Level to ADVISORY.
Eruptive activity at Shishaldin paused after the explosion on January 19, 2020, before resuming at a low level mid-March. It is therefore possible for eruptive activity to resume with little warning and AVO will continue to monitor the volcano closely.
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:||na|
|(13) Other volcanic cloud information:||na|
|(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:||Michelle Coombs, Scientist-in-Charge, USGS
email@example.com (907) 786-7497
David Fee, Coordinating Scientist, UAFGI
firstname.lastname@example.org (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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