Chirpoi volcano forms a small island in the central Kurile Islands, Russia. It has a 8-9 km wide partially submerged caldera with several volcanic centers inside the caldera, including active Snow and Cerny volcanoes. The southern caldera rim emerges again on nearby Brat Chirpoey Island 2.5 km SE of Chirpoi.
Only 2 volcanoes on Chirpoi Island have been historically active: The symmetrical Cherny volcano which forms the highest peak erupted 2 times. The second, younger and more active volcano is Snow. Snow volcano formed between 1770 and 1810 and is composed almost entirely of lava flows, many of which have reached the sea on the southern coast.
There are no historical eruptions on Brat Chirpoev, but its youthful morphology suggests recent strombolian activity.
