|(1) VOLCANO OBSERVATORY NOTICE FOR AVIATION (VONA)|
|(3) Volcano:||Semisopochnoi (VNUM #311060)|
|(4) Current Color Code:||ORANGE|
|(5) Previous Color Code:||YELLOW|
|(6) Source:||Alaska Volcano Observatory|
|(7) Notice Number:||2021/A70|
|(8) Volcano Location:||N 51 deg 55 min E 179 deg 35 min|
|(10) Summit Elevation:||2625 ft (800 m)|
|(11) Volcanic Activity Summary:||Regional infrasound sensors detected a small explosion from Semisopochnoi volcano this morning at 11:50 UTC (03:50 AKDT), indicating an increase in eruptive activity. As a result, AVO is raising the Aviation Color Code to ORANGE and the Volcano Alert Level to WATCH. Cloudy weather conditions are obscuring satellite views of the volcano. It is unknown if the explosion produced a low-level ash cloud or local ash deposit.
Small eruptions producing minor ash deposits within the vicinity of the volcano are typical of activity during unrest at Semisopochnoi since September 2018. Local seismic stations have been offline since November 11, 2020. New explosions could occur at anytime with no warning.
|(12) Volcanic cloud height:||n/a|
|(13) Other volcanic cloud information:||n/a|
|(14) Remarks:||Semisopochnoi is monitored 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:||Matthew Haney, Acting Scientist-in-Charge, USGS
firstname.lastname@example.org (907) 786-7497
David Fee, Coordinating Scientist, UAFGI
email@example.com (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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