|(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:|
|(8) Volcano Location:||N 51 deg 55 min E 179 deg 35 min|
|(10) Summit Elevation:||2625 ft (800 m)|
|(11) Volcanic Activity Summary:||Elevated seismicity that began yesterday has increased overnight. A stronger tremor signal recorded at 23:39 AKDT / 07:39 UTC also produced an infrasound signal on an infrasound array 260 km (161 miles) east on Adak island. This event likely produced ash emissions, and at the current level of continued unrest similar events could occur with little to no warning. The meteorological cloud deck has been around 10,000' (3000 m) asl over Semisopochnoi and no ash signals have been detected above this height. A small plume extending 18 km (11 miles) from the Cerberus vent was visible in satellite data from yesterday, but did not contain an ash signal.
Nothing has been detected in lightning data.
|(12) Volcanic cloud height:||No cloud observed|
|(13) Other volcanic cloud information:||No cloud observed|
|(14) Remarks:||Semisopochnoi is monitored with an on-island seismic network, and 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:||Michelle Coombs, Scientist-in-Charge, USGS
firstname.lastname@example.org (907) 786-7497
Jessica Larsen, Acting 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
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