Tolbachik volcano viewed from the southeast. The volcano is built
by two coalesced cones: Ostry ("Sharp") Tolbachik (at the
left) and Plosky ("Flat") Tolbachik. Ostry Tolbachik was
partly destroyed by a sector collapse ~6.5 ka BP. Plosky Tolbachik
is crowned by a summit caldera, which hosts a small shield volcano
hidden under a glacier. Smaller caldera and a modern crater intermittently
filled with lava are nested in the western part of the larger caldera.