(1) VOLCANO OBSERVATORY NOTICE FOR AVIATION (VONA)
 (2) Issued:20251023/2307Z
 (3) Volcano:Klyuchevskoy (CAVW #300260)
 (4) Current aviation colour code:YELLOW
 (5) Previous aviation colour code:orange
 (6) Source:KVERT
 (7) Notice Number:2025-122
 (8) Volcano Location:N 56 deg 3 min E 160 deg 38 min
 (9) Area:Kamchatka, Russia
(10) Summit Elevation:4750 m (15580 ft)
(11) Volcanic Activity Summary:The explosive-effusive eruption of the Klyuchevskoy volcano, which lasted from 20 April to 16 August, 2025, has ended. The explosive eruption ended, but the magma column continues to subside deeper into the volcano's edifice, resulting in occasional ash emissions from the volcano's crater. According to KVERT visual and satellite data, gas-steam plumes extended for 245 km in various directions from the volcano on 16-17 and 20-23 October; a large thermal anomaly associated with the cooling of the lava flow was observed on its western slope all week.

A gas-steam activity of the volcano continues. The danger of ash emissions up to 8 km (26,200 ft) a.s.l. remains. Ongoing activity could affect low-flying aircraft.
(12) Volcanic cloud height:NO ASH CLOUD PRODUSED
(13) Other volcanic cloud information:NO ASH CLOUD PRODUSED
(14) Remarks:
(15) Contacts:Dr. Olga A. Girina, Head of KVERT, IVS FEB RAS
girina@kscnet.ru +74152202044

Duty scientist: +79622825253
(16) Next Notice:A new VONA will be issued if conditions change significantly or the colour code is changed. VONAs are posted at http://kvert.febras.net.

In Russia, KVERT, on behalf of the Institute of Volcanology and Seismology (IVS) FEB RAS, is responsible for providing information on volcanic activity to international air navigation services for the airspace users.

CITATION GUIDELINES

For formal scientific citation of this KVERT Volcanic Activity Notice, please use the following:
KVERT Volcanic Activity Notice, October 23, 2025. KVERT, Institute of Volcanology and Seismology FEB RAS. URL: http://kvert.febras.net/van/?n=2025-122.
Aviation Colour Codes

GREEN

Volcano is in normal, non-eruptive state
   or, after a change from a higher level:
Volcanic activity considered to have ceased, and volcano reverted to its normal, non-eruptive state.

YELLOW

Volcano is experiencing signs of elevated unrest above known background levels.
 or, after a change from higher level:
Volcanic activity has decreased significantly but continues to be closely monitored for possible renewed increase.

ORANGE

Volcano is exhibiting heightened unrest with increased likelihood of eruption.
   or,
Volcanic eruption is underway with no or minor ash emission.
[specify ash-plume height if possible]

RED

Eruption is forecast to be imminent with significant emission of ash into the atmosphere likely.
  or,
Eruption is underway with significant emission of ash into the atmosphere.
[specify ash-plume height if possible]

UNASSIGNED

There is insufficient information available to assess the current status of the volcano or volcanic activity.