(1) VOLCANO OBSERVATORY NOTICE FOR AVIATION (VONA) | |
(2) Issued: | (20200401/2016Z) |
(3) Volcano: | Semisopochnoi (VNUM #311060) |
(4) Current Color Code: | YELLOW |
(5) Previous Color Code: | ORANGE |
(6) Source: | Alaska Volcano Observatory |
(7) Notice Number: | |
(8) Volcano Location: | N 51 deg 55 min E 179 deg 35 min |
(9) Area: | Aleutians |
(10) Summit Elevation: | 2625 ft (800 m) |
(11) Volcanic Activity Summary: | Seismic, infrasound, and satellite data over the past two weeks have shown no signs of eruptive activity at Semisopochnoi. A robust steam plume and a crater lake have been seen in clear satellite images, but no recent ash deposits. Although seismic activity remains above background, it does not appear to be increasing towards an eruption in the short-term. Thus, AVO is reducing the Aviation Color Code to YELLOW and the Volcano Alert Level to ADVISORY. Unrest continues. Seismic activity persists and is characterized by occasional small earthquakes and satellite data show detectable volcanic gas (sulfur dioxide) being emitted from the volcano. Explosive activity could resume with little to no warning. |
(12) Volcanic cloud height: | n/a |
(13) Other volcanic cloud information: | n/a |
(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 mcoombs@usgs.gov (907) 786-7497 David Fee, Coordinating Scientist, UAFGI dfee1@alaska.edu (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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