Global Volcanism Program | Image GVP-02432
During the 1975-76 eruption a new collapse caldera formed within the Plosky Tolbachik main summit caldera. The eruption occurred along the SSW-flank rift zone 18 km away. Collapse began on 18 July following minor ash eruptions that began on 28 June. By mid-September the diameter of the caldera reached 1.2 x 1.6 km, and the depth increased from 230 to 400 m. The summit of Udina appears above the clouds to the SE.
Photo by Dan Miller, 1990 (U.S. Geological Survey).
This image is made available as a Public Domain Work, but proper attribution is appreciated.