Before the Kurile Lake caldera formed, the Pauzhetka caldera was active during the Pleistocene, and was the origin of the 443,000 ± 8,000 years old Golygin ignimbrite. The Kurile Lake caldera erupted 41,500 years ago, and another small eruption occurred between 9,000 and 10,000 years ago; then 6460-6414 BC a very large eruption took place, forming the present-day caldera and the Kurile Lake ignimbrite and deposited ash as far as away. This eruption has a volume of , making it a VEI 7-class eruption and one of the largest during the Holocene. Subsequently, the volcanoes Diky Greben and Ilinsky grew around the caldera; the last eruption from Ilinsky was in 1911. The caldera is filled by a lake with an area of , and a maximum depth of . It contains the largest sockeye salmon stocks in Asia.