Report on Zavaritzki Caldera (Russia) — December 1981
Scientific Event Alert Network Bulletin, vol. 6, no. 12 (December 1981)
Managing Editor: Lindsay McClelland.
Zavaritzki Caldera (Russia) No fumarolic activity
Please cite this report as:
Global Volcanism Program, 1981. Report on Zavaritzki Caldera (Russia). In: McClelland, L. (ed.), Scientific Event Alert Network Bulletin, 6:12. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198112-290180.
46.925°N, 151.95°E; summit elev. 624 m
All times are local (unless otherwise noted)
No apparent fumarolic or solfataric activity was observed [during an aerial inspection of Kuril Island volcanoes on 20 September 1981].
Geologic Background. Zavaritzki volcano in central Simushir Island contains three nested calderas of 10-, 8-, and 3-km diameter. The steep-walled youngest caldera was formed during the Holocene and contains a lake whose surface is about 40 m elevation and whose bottom lies about 30 m below sea level. Several young cones and lava domes are located near the margins of Biryuzovoe caldera lake. Lacustrine sediments overlying pumice deposits indicate that an earlier caldera lake lay at 200 m above sea level, well above the present lake surface. Two eruptions have occurred at Zavaritzki during the 20th century. A lava dome that was emplaced sometime between 1916 and 1931 forms a small island in the northern part of the caldera lake. In 1957, a new 350-m-wide, 40-m-high dome was emplaced following explosive eruptions, decreasing the size of the caldera lake.
Information Contacts: G. Steinberg, Sakhalin Complex Institute.