Iliinsky

Geography & Climate

Iliinsky is located in Russia, within the Kuril Volcanic Arc of the broader Northwestern Pacific Volcanic Regions. Situated at 51.50° N, 157.20° E in the Northern Hemisphere, the volcano lies within a temperate climate zone. With a summit elevation of 1,555 meters above sea level, Iliinsky 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

Iliinsky 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 Iliinsky, 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

Iliinsky has 6 recorded eruptions in the geological database, spanning from 5700 BCE to 1901 CE. The most powerful recorded event was a paroxysmal eruption with devastating regional consequences in 2850 BCE, reaching VEI 5 on the Volcanic Explosivity Index. Notable eruptions include 1901 CE (VEI 3), 2850 BCE (VEI 5), 5700 BCE (VEI 4). This eruption frequency indicates a moderately active volcanic system with periodic reawakenings. The most recent eruption in 1901 CE places this volcano within the modern era of volcanological observation.

Significance

With a maximum recorded VEI of 5, Iliinsky has demonstrated the capacity for paroxysmal eruptions comparable to the 1980 eruption of Mount St. Helens. Eruptions of this scale can devastate areas within 20-30 kilometers and produce ash fall that disrupts aviation and agriculture across hundreds of kilometers. With 6 recorded eruptions on file, Iliinsky has enough documented activity to help scientists identify patterns in its eruptive behavior.

GVP Reference Summary

The conical Iliinsky volcano (also spelled Ilyinsky), rising dramatically to 1555 m above the NE shore of Kurile Lake, was constructed beginning about 7600 radiocarbon years ago at the NE margin of Kurile Lake caldera. The modern edifice grew within a 4-km-wide caldera produced by collapse of an earlier volcano creating large debris avalanches at about the time of formation of the adjacent Kurile Lake caldera. A period of strong silicic explosive volcanism during the mid-Holocene lasted about 800 years. A series of youthful lava flows cover much of the northern flanks. Growth of the modern cone was completed about 1900 years ago, after which a long quiescent period began. The only recorded historical eruption, in 1901, produced a large 1-km-wide crater on the NE flank.

— Smithsonian Institution, Global Volcanism Program