|(1) VOLCANO OBSERVATORY NOTICE FOR AVIATION (VONA)|
|(3) Volcano:||Semisopochnoi (VNUM #311060)|
|(4) Current Color Code:||ORANGE|
|(5) Previous Color Code:||ORANGE|
|(6) Source:||Alaska Volcano Observatory|
|(7) Notice Number:||2021/A188|
|(8) Volcano Location:||N 51 deg 55 min E 179 deg 35 min|
|(10) Summit Elevation:||2625 ft (800 m)|
|(11) Volcanic Activity Summary:||Eruptive activity at Semisopochnoi has gradually increased over the last 24 hours. Satellite views of the volcano show a continuous plume extending 50 miles (80 km) to the south at approximately 8000 feet a.m.s.l. A regional infrasound array has detected this increase in activity. The aviation color code and alert level remain at ORANGE/WATCH; however, AVO will continue to monitor the activity with satellite and regional infrasound data.
Small eruptions producing minor ash deposits within the vicinity of the volcano and ash clouds under 10,000 ft above sea level are typical of activity at this volcano.
|(12) Volcanic cloud height:||8000 ft a.m.s.l.|
|(13) Other volcanic cloud information:||unknown|
|(14) Remarks:||Semisopochnoi is monitored by satellite data, regional infrasound, and lightning detection instruments. An infrasound array on Adak Island may detect explosive emissions from Semisopochnoi with a slight delay (approximately 13 minutes) if atmospheric conditions permit.|
|(15) Contacts:||Matt Haney, Acting Scientist-in-Charge, USGS
firstname.lastname@example.org (907) 786-7497
Jessica Larsen, Acting Coordinating Scientist, UAF
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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