Vilyuchinsky, or Vilyuchik, is a steep-sided Pleistocene-to-Holocene stratovolcano south of Avachinsky Bay. Deep erosional gullies dissect the flanks, with Lava domes and young basaltic cinder cones at its base. Most of the growth of the volcano took place during the late Pleistocene. The last significant eruption took place from the summit crater about 10,000 years ago, producing a moderate airfall deposit and a lava flow. Landslides and rock avalanches have affected habited areas.