V.I. Bondarenko1, V.A.Rashidov2

1State Nekrasov University of Kostroma, 15600 Kostroma 1 May street, 14.
Fax: (0942)3111322; e-mail: kgpu@kosnet.ru
2Institute of Volcanic Geology and Geochemistry FED RAS, 683006, Petropavlovsk-Kamchatsky, Piip Blvd., 9.
Fax: (415-22)59130; e-mail: rashidva@kscnet.ru

Two calderas can be distinguished within the Chernye Bratia volcanic massif: Gorshkov caldera and Outer Gorshkov caldera. Chernye Bratia islands host 13 volcanic edifices including three active ones. Chirpoi island is characterized by high fumarolic activity. During marine volcanological survey several acoustic anomalies were registered probably indicating submarine gas-hydrothermal activity within the massif.