| (1) VOLCANO OBSERVATORY NOTICE FOR AVIATION (VONA) | |
| (2) Issued: | (20191207/1025Z) |
| (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 |
| (9) Area: | Aleutians |
| (10) Summit Elevation: | 2625 ft (800 m) |
| (11) Volcanic Activity Summary: | An eruption signature was detected as strong tremor on local seismic and in regional infrasound networks on Adak Island. The event started at 00:26 AKST / 09:26 UTC and has continued with and ongoing but weaker local seismic signal. Any volcanic ash emissions are most likely low-level. The meteorological cloud deck has been around 10,000' (3000 m) asl over Semisopochnoi and no ash signals have been detected above this height. 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 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 |