Before the eruption, a 1,500 year lull in volcanic activity allowed the deposition of soils in the area. A minor eruption occurred at Kurile Lake between 9,000 and 10,000 years ago, resulting in the deposition of tephra north of the caldera. This tephra is formed by gray fine ash and lapilli consisting of dacitic pumice. Other volcanoes also left several tephra deposits. Soils formed after the caldera forming eruptions also contain a number of ash layers by volcanoes both near and far. Volcanic activity occurred at Ilinsky volcano after the caldera forming eruption until 1901, and the similarity between Ilinsky and Kurile Lake rocks indicate that the activities of the two centres are related. Diky Greben formed less than 100 years after the formation of the caldera and was last active 1600 BP. A number of other lava domes and pyroclastic cones formed inside the caldera shortly after the caldera-forming eruption.