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AVO/USGS Volcanic Activity Notice

Volcano: Okmok (VNUM #311290)

Current Volcano Alert Level: UNASSIGNED
Previous Volcano Alert Level: NORMAL

Current Aviation Color Code: UNASSIGNED
Previous Aviation Color Code: GREEN


Issued: Tuesday, January 28, 2025, 5:01 PM AKST
Source: Alaska Volcano Observatory
Notice Number: 2025/A57
Location: N 53 deg 23 min W 168 deg 9 min
Elevation: 3520 ft (1073 m)
Area: Aleutians

Volcanic Activity Summary:

The Alaska Volcano Observatory (AVO) equipment that transmits real-time seismic data from stations in the Okmok volcano monitoring network has experienced significant degradation over the past several days. A few channels are still being transmitted but are not sufficient to establish that the volcano is at a typical background level. AVO estimates that the outage will likely last several weeks or longer. As a result, AVO is unable to (1) assess whether this volcano may be building towards an eruption and (2) quickly confirm or dismiss reports of activity.

Because this volcano is no longer monitored at adequate levels, the Aviation Color Code and Volcano Alert Level are changed to UNASSIGNED/UNASSIGNED.  As at other volcanoes without real-time seismic networks, AVO will continue to use satellite data, regional seismic, infrasound and lightning networks, and reports from pilots and ground observers to detect signs of eruptive activity.



Recent Observations:
[Volcanic cloud height] none
[Other volcanic cloud information] none
[Ballistics] none
[Lava flow/dome] none
[Lava flow] none

Hazard Analysis:
[General hazards] none
[Ash cloud] none
[Ashfall] none
[Lava flow/dome] none
[Pyroclastic flow] none
[Mud flow] none
[Volcanic gas] none
[Other hazards] none
[Lava flow] none

Remarks:

Okmok volcano is a 6-mile-wide caldera that occupies most of the eastern end of Umnak Island, located 75 miles southwest of Unalaska/Dutch Harbor in the eastern Aleutian Islands. Okmok has had several eruptions in historic time typically consisting of ash emissions occasionally to over 30,000 feet ASL but generally much lower; lava flows crossed the caldera floor in 1945 and 1958. Prior to 2008, the volcano last erupted in February 1997 producing lava flows and intermittent ash emissions over the course of several months. The nearest settlement is Nikolski, population about 35, roughly 45 miles west of the volcano.



Contacts:

Matt Haney, Scientist-in-Charge, USGS mhaney@usgs.gov (907) 786-7497

David Fee, Coordinating Scientist, UAFGI dfee1@alaska.edu (907) 378-5460



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







The Alaska Volcano Observatory is a cooperative program of the U.S. Geological Survey, the University of Alaska Fairbanks Geophysical Institute, and the Alaska Division of Geological and Geophysical Surveys.

(1) VOLCANO OBSERVATORY NOTICE FOR AVIATION (VONA)
(2) Issued: (20250129/0201Z)
(3) Volcano: Okmok (VNUM #311290)
(4) Current Color Code: UNASSIGNED
(5) Previous Color Code: GREEN
(6) Source: Alaska Volcano Observatory
(7) Notice Number: 2025/A57
(8) Volcano Location: N 53 deg 23 min W 168 deg 9 min
(9) Area: Aleutians
(10) Summit Elevation: 3520 ft (1073 m)
(11) Volcanic Activity Summary:

The Alaska Volcano Observatory (AVO) equipment that transmits real-time seismic data from stations in the Okmok volcano monitoring network has experienced significant degradation over the past several days. A few channels are still being transmitted but are not sufficient to establish that the volcano is at a typical background level. AVO estimates that the outage will likely last several weeks or longer. As a result, AVO is unable to (1) assess whether this volcano may be building towards an eruption and (2) quickly confirm or dismiss reports of activity.

Because this volcano is no longer monitored at adequate levels, the Aviation Color Code and Volcano Alert Level are changed to UNASSIGNED/UNASSIGNED.  As at other volcanoes without real-time seismic networks, AVO will continue to use satellite data, regional seismic, infrasound and lightning networks, and reports from pilots and ground observers to detect signs of eruptive activity.

(12) Volcanic cloud height: none
(13) Other volcanic cloud information: none
(14) Remarks:

Okmok volcano is a 6-mile-wide caldera that occupies most of the eastern end of Umnak Island, located 75 miles southwest of Unalaska/Dutch Harbor in the eastern Aleutian Islands. Okmok has had several eruptions in historic time typically consisting of ash emissions occasionally to over 30,000 feet ASL but generally much lower; lava flows crossed the caldera floor in 1945 and 1958. Prior to 2008, the volcano last erupted in February 1997 producing lava flows and intermittent ash emissions over the course of several months. The nearest settlement is Nikolski, population about 35, roughly 45 miles west of the volcano.

(15) Contacts:

Matt Haney, Scientist-in-Charge, USGS mhaney@usgs.gov (907) 786-7497

David Fee, Coordinating Scientist, UAFGI dfee1@alaska.edu (907) 378-5460

(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


Hazard Notification System (HANS) for Volcanoes at volcanoes.usgs.gov/hans2/