Klyuchevskoy (Russia): Recorded Eruptions and Historical Activity

Klyuchevskoy is a stratovolcano located in Russia at an elevation of 4,754 meters within a subduction zone and continental crust tectonic setting (latitude 56.056, longitude 160.642). Official records from the Smithsonian Global Volcanism Program document 111 confirmed eruptions spanning thousands of years, with the earliest recorded year dating to 3950 BCE and the latest recorded activity extending through 2025 CE.

Overview of Recorded Eruptions

The historical and prehistoric record for Klyuchevskoy includes 111 confirmed eruptions evaluated through various evidence methods, ranging from uncalibrated radiocarbon dating for ancient events to direct human observations for more recent centuries. Across the entire recorded timeline, the largest assigned Volcanic Explosivity Index (VEI) reaches 4.0. Out of the 111 confirmed eruptions, 107 have associated VEI observations.

Representative examples from the record illustrate the diverse nature of the volcano's activity over time:

• 3950 BCE: An early recorded event identified via uncalibrated carbon-14 isotopic evidence (start date noted with a modifier as 3950 BC).
• 1853–1854 CE: A confirmed eruption lasting from October 16, 1853, to February 17, 1854, assigned a VEI of 2.0 based on reported observations.
• 1944–1945 CE: A reported observational eruption occurring between December 9, 1944, and January 20, 1945, with a VEI of 3.0.
• 1986–1990 CE: An extensive eruption spanning from November 27, 1986, to September 16, 1990, affecting multiple areas including the summit, southeast, southwest, northeast, and east flanks, reaching a VEI of 4.0.
• 2025 CE: A reported eruption starting on April 8, 2025, and concluding on August 16, 2025, with a VEI of 3.0.

Eruption Frequency by Century

The structured record shows that documented activity is unevenly distributed across centuries, heavily weighted toward periods with written historical observations. The distribution of confirmed eruptions by century includes:

• 40th century BCE: 1 eruption
• 11th century BCE: 1 eruption
• 6th century CE: 1 eruption
• 17th century CE: 1 eruption
• 18th century CE: 15 eruptions
• 19th century CE: 19 eruptions
• 20th century CE: 57 eruptions
• 21st century CE: 16 eruptions

Variations in eruption counts between ancient millennia and modern centuries reflect both changes in actual volcanic behavior and differences in the completeness of human observation and historical documentation.