Kolokol Group

Geography & Climate

Kolokol Group is located in Russia, within the Kuril Volcanic Arc of the broader Northwestern Pacific Volcanic Regions. Situated at 46.04° N, 150.08° E in the Northern Hemisphere, the volcano lies within a temperate climate zone. With a summit elevation of 1,328 meters above sea level, Kolokol Group is a moderately sized peak that remains accessible to hikers and researchers for much of the year. The volcanic landform is characterized as a composite, which describes the physical shape and structure of the volcanic edifice as observed from the surface.

Geological Context

Kolokol Group sits in a subduction zone, where one tectonic plate dives beneath another, creating intense heat and pressure that generates magma. Subduction zones are responsible for many of the world's most explosive volcanoes and deadliest eruptions. For communities in Russia near Kolokol Group, this tectonic setting means the volcano is capable of producing powerful explosive eruptions, pyroclastic flows, and lahars that can threaten populated areas within tens of kilometers of the summit. The dominant rock type is andesite / basaltic andesite, a dark, fine-grained volcanic rock that forms from rapidly cooling, low-viscosity lava. Basaltic eruptions tend to be less explosive and produce fluid lava flows that can travel long distances. While less immediately dangerous than explosive eruptions, basaltic lava flows can destroy structures and infrastructure in their path, and volcanic gases released during these eruptions can affect air quality over a wide area.

Eruption History Summary

Kolokol Group has 11 recorded eruptions in the geological database, spanning from 1780 CE to 2009 CE. The most powerful recorded event was a severe eruption capable of regional ash fall and pyroclastic flows in 1970 CE, reaching VEI 3 on the Volcanic Explosivity Index. This level of eruptive frequency indicates a persistently active volcanic system that warrants ongoing monitoring. With eruptive activity as recently as 2009 CE, Kolokol Group remains an actively monitored volcano.

Significance

With a maximum recorded VEI of 3, Kolokol Group has produced eruptions capable of generating pyroclastic flows and significant ash fall in the surrounding area. While not among the largest eruptions globally, VEI 3 events pose serious hazards to local populations and can disrupt regional air travel. With 11 recorded eruptions, Kolokol Group has a substantial eruptive history that provides valuable data for understanding volcanic behavior and assessing future hazards in the Northwestern Pacific Volcanic Regions region. Given its recent activity, Kolokol Group is closely monitored by geological survey organizations to provide early warning of future unrest.

GVP Reference Summary

A group of Holocene volcanoes in central Urup Island is named after its most prominent volcano, Kolokol. Berg and Trezubetz volcanoes, flanking Kolokol on the NW, have breached summit calderas partially filled by lava domes. Trezubetz, whose name means "Trident," has an eroded crater rim with three large peaks when seen at sea from the north. Kolokol is sometimes known as Urup-Fuji because of its symmetrical profile. The crater of Kolokol is not well preserved, but there is no evidence of glacial erosion. Several lava flows originate from Kolokol; one of these extends almost to the Sea of Okhotsk coast; a viscous lava flow armoring the SE flank is probably the most recent. Borzov volcano, the oldest of the group, lies to the SW of Kolokol. Eruptions have been observed since the late-18th century. Berg volcano has been most active, but Trezubetz erupted in 1924.

— Smithsonian Institution, Global Volcanism Program