Klyuchevskoy

At 4,754 m (15,597 ft), Klyuchevskoy is the highest active volcano in all of Eurasia — taller than Mont Blanc and nearly as high as Mount Rainier.

The volcano is only approximately 6,000 years old, yet has built a symmetrical cone rising 3,000 m above its base — making it one of the fastest-growing volcanic edifices on Earth.

With 113 recorded eruptions and an average recurrence interval of roughly 3 years, Klyuchevskoy is the most active volcano in the Northern Hemisphere outside of Iceland.

The 1986–1990 eruption lasted approximately four years, produced ash clouds to 15 km altitude, and was rated VEI 4 — the volcano's most powerful event in over 150 years.

Klyuchevskoy's summit crater is approximately 700 m wide, but its shape changes with nearly every major eruption as explosions destroy and rebuild the rim.

The volcano sits directly beneath one of the busiest aviation corridors in the world, with over 200 commercial flights per day crossing the North Pacific — making its ash clouds a global transportation hazard.

The Klyuchevskaya volcanic group contains 13 volcanoes in close proximity, forming one of the most concentrated volcanic landscapes on the planet.

More than 100 flank eruptions over the past 3,000 years have produced lateral craters and cinder cones across the NE-to-SE flanks between 500 and 3,600 m elevation.

The first recorded summit ascent was by military topographer Daniil Gauss in 1788, making it one of the earliest documented high-altitude climbs in Russian history.

Klyuchevskoy produces roughly 60 million cubic meters of new volcanic material per century, continuously building its near-perfect cone without major collapse events.

Three VEI 4 eruptions have occurred in the historical record (1829, 1931, 1986–1990) — the most VEI 4+ events at any single volcano in Kamchatka.

The nearby volcano Bezymianny produced a catastrophic lateral blast in 1956 that was later recognized as a precursor analogue for the 1980 Mount St. Helens eruption.