This extinct stratovolcano, also known as Apalskaia sopka or Apachinskaia sopka, is located in the northern portion of its caldera which stretches 10-12 km in diameter. Near the summit and at the foot of the southeastern slope remains well preserved lava flows.
The formation of this caldera coincided with an eruption of pumice ash-flows that deposited and average thickness of 50 m in this area. From the data of radiocarbon dated fossils that are covered by tuffs associated with the caldera, it has been determined that Opala caldera was formed between about 31 to 39 thousand years before the present. Opala volcano has a diameter of 8.5 km. Near the southeast slopes of Opala is located a large crater (1.3 x 2 km) called Barany Amphitheater. Eruptions have been observed from as far away as Bolsheretsk which is 100 km from Opala. An explosive eruption was observed in 1776. Some other volcanoes in this local area are: Mutnovsky, Asacha, and Bolshaya Ipelka.
Sources of Information:
Erlich, Edward 1986 Geology of Calderas of Kamchatka and Kurile Islands with Comparison to Calderas of Japan and the Aleutians, Alaska Open-File Report 86-291, US Dept. of the Interior- Geological Survey, p108-10.
Vlodavetz V.I., Piip B. I. 1959 Kamchatka and Continental Areas of Asia. Catalog of Active Volcanoes of the World, Rome IAVCEI, 8: p19-20.