Koryaksky

Koryaksky, also known as Koryakskaya Sopka, is an active volcano located on the Kamchatka Peninsula in Russia’s Far East. It is visible from Petropavlovsk-Kamchatsky, the administrative center of Kamchatka Krai. Along with the nearby Avachinsky volcano, it is classified as a Decade Volcano—a designation given to volcanoes that merit close study due to their explosive eruption history and their closeness to populated areas.

The volcano sits on the Pacific Ring of Fire, where the Pacific Plate slides beneath the Eurasian Plate at a rate of roughly 80 millimeters per year. A wedge of mantle material between the subducting Pacific Plate and the overlying Eurasian Plate drives the widespread volcanic activity across the Kamchatka Peninsula.

Koryaksky has likely been active for tens of thousands of years. Geological evidence points to three major eruptions over the past 10,000 years, occurring around 5500 BC, 1950 BC, and 1550 BC. These events were mostly effusive, producing extensive lava flows.

The first recorded eruption in history took place in 1890, marked by lava emissions from fissures on the volcano’s southwestern flank and phreatic explosions. An apparent eruption five years later was later determined to be nothing more than steam from strong fumarolic activity. A brief, moderately explosive eruption followed in 1926, after which the volcano remained dormant until 1956.

That eruption was more explosive than any previously known, with a Volcanic Explosivity Index (VEI) of 3, and generated pyroclastic flows and lahars. It continued until June 1957. On December 29, 2008, Koryaksky erupted again, sending a 6,000-meter ash plume into the sky—the first major eruption in 3,500 years.

Because of its proximity to Petropavlovsk-Kamchatsky, Koryaksky was named a Decade Volcano in 1996 as part of the United Nations’ International Decade for Natural Disaster Reduction, alongside the neighboring Avachinsky volcano.