| (1) VOLCANO OBSERVATORY NOTICE FOR AVIATION (VONA) | |
| (2) Issued: | (20220422/0102Z) |
| (3) Volcano: | Davidof (VNUM #311040) |
| (4) Current Color Code: | UNASSIGNED |
| (5) Previous Color Code: | YELLOW |
| (6) Source: | Alaska Volcano Observatory |
| (7) Notice Number: | 2022/A443 |
| (8) Volcano Location: | N 51 deg 57 min E 178 deg 19 min |
| (9) Area: | Aleutians |
| (10) Summit Elevation: | 1076 ft (328 m) |
| (11) Volcanic Activity Summary: | A swarm of earthquakes near Davidof volcano that began in late January 2022 has been in a slow decline over the past few weeks. Thus, the Aviation Color Code and Alert Level are being decreased to UNASSIGNED/UNASSIGNED. AVO only assigns color code and alert level values to volcanoes that are sufficiently instrumented to allow us to understand the background state of activity. The closest seismometers to Davidof are approximately 15 km to the east of the volcano on Little Sitkin Island, and are insufficient to allow us to confirm the volcano is at background. A similar earthquake swarm occurred in December 2021. No signs of unrest associated with either swarm have been observed in satellite images of the volcano. The earthquake activity may be associated with volcanic unrest, or could be due to tectonic activity. |
| (12) Volcanic cloud height: | n/a |
| (13) Other volcanic cloud information: | n/a |
| (14) Remarks: | Davidof volcano is a mostly submerged stratovolcano in the Rat Islands group in the western Aleutian Islands, about 350 km west of Adak. The subaerial part of the volcano comprises Davidof, Khvostof, Pyramid, and Lopy islands, which encircle Crater Bay, a 2.5 km diameter caldera. The islands are built up from interbedded lava flows and explosive deposits. The volcano has been sparsely studied, but visits by Alaska Volcano Observatory geologists in 2021 documented thick sequences of rhyolite to dacite pyroclastic flow and fall deposits that represent the most recent explosive eruptions. The age of these deposits is unknown, but they appear older than Holocene deposits from nearby Segula and Little Sitkin. There are no known historical eruptions from Davidof. |
| (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: | |