USGS Volcano Notice - DOI-USGS-AVO-2026-09-08T22:30:01+00:00

AVO/USGS Volcanic Activity Notice

Volcano: Kupreanof (VNUM #312060)

Current Volcano Alert Level: UNASSIGNED
Previous Volcano Alert Level: ADVISORY

Current Aviation Color Code: UNASSIGNED
Previous Aviation Color Code: YELLOW

Issued: Tuesday, September 8, 2026, 2:31 PM AKDT
Source: Alaska Volcano Observatory
Notice Number: 2026/A699
Location: N 56 deg W 159 deg 47 min
Elevation: 6217 ft (1895 m)
Area: Alaska Peninsula

Summary: Volcanic activity at Mount Kupreanof has declined to background levels.

Volcanic Activity:

[CORRECTED] The number of earthquakes, intensity of steam emissions, and measured sulfur dioxide emissions beneath Mount Kupreanof have declined. Due to these changes, the Alaska Volcano Observatory is lowering the Aviation Color Code and the Volcano Alert Level to UNASSIGNED.

Summary of activity and hazards

Seismicity was first detected in February 2026 and increased over the following months, with earthquakes as large as magnitude 3.1 recorded. However, seismicity has declined over the past month.
Sulfur dioxide (SO₂) emissions were detected beginning on April 4 with emission rates of ~100 to 1,000 tons per day, which are well above the background rate of <100 tons per day. These have dropped to background levels since late August.
Collectively, these data likely indicate the magmatic intrusion beneath Mount Kupreanof has stalled.

Additional information:

The Aviation Color Code and the Volcano Alert Level are being changed to UNASSIGNED, rather than GREEN and NORMAL, due to insufficient coverage by ground-based monitoring data.
An AVO Information Statement from May 8, 2026, gives further details about this activity and interpretations: https://avo.alaska.edu/news/hans/DOI-USGS-AVO-2026-05-08T19:12:14+00:00
Learn more about Mount Kupreanof and its current monitoring data on the AVO website: https://avo.alaska.edu/volcano/kupreanof

Remarks:

Mount Kupreanof is a heavily glaciated stratovolcano on the Alaska Peninsula with no known historical eruptions. Very little is known about its eruptive history. A single debris flow or block-and-ash flow deposit with a suspected Holocene age has been mapped in a valley south of the volcano. Eruptions will likely produce lahars and pyroclastic flows on the volcano's flanks and into the surrounding uninhabited valleys. Ash plumes could affect communities and airplanes downwind of the volcano. A vigorous fumarole field just west of the summit produces persistent steam plumes.

A new temporary monitoring station was installed near Mount Kupreanof this past summer (2026) and is providing seismic data, infrasound data, gas measurements, and web camera images on an intermittent basis. This is by design to conserve battery power, but the frequency of data acquisition can be increased if activity warrants. The closest functioning seismometers that provide continuous data are approximately 10 miles (16 km) to the northeast of the volcano as part of the Mount Veniaminof network. Mount Kupreanof is also monitored by satellite data, remote infrasound and lightning networks, and visual observations from pilots and mariners passing by 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

Contact AVO: https://avo.alaska.edu/contact

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.

VOLCANO OBSERVATORY NOTICE FOR AVIATION (VONA)

WMAK01 PAVO 082231   
VONA
DTG:                    20260908/2231Z
VOLCANO:                KUPREANOF 312060
PSN:                    N5601 W15947
AREA:                   ALASKA
SOURCE ELEV:            6217FT AMSL
NOTICE NR:              2026/03
CURRENT COLOUR CODE:    UNASSIGNED
PREVIOUS COLOUR CODE:   YELLOW
SVO:                    ALASKA VOLCANO OBSERVATORY
ACT STS:                DECREASED UNREST
ONSET:                  NIL
DUR:                    NIL
VA CLD HGT:             NO VA CLD PRODUCED
HGT SOURCE:             NO VA CLD PRODUCED
MOV:                    NO VA CLD PRODUCED
CTC:                    AVO DUTY SCIENTIST 907-786-7497
RMK:                    [CORRECTED] VOLCANIC ACTIVITY HAS DECLINED. AVIATION COLOR CODE IS UNASSIGNED RATHER
                        THAN GREEN DUE TO INSUFFICIENT GROUND-BASED MONITORING DATA.
NXT NOTICE:             A NEW VONA WILL BE ISSUED IF COND CHANGE SIGNIFICANTLY OR IF THE COLOR CODE CHANGES
NNNN