noun
caldera
Geological term for a large volcanic crater formed by collapse after an eruption.
阿蘇山には世界最大級のカルデラがある。
Mount Aso has one of the largest calderas in the world.
火口 is a general term for a volcanic crater, while カルデラ specifically refers to a large, collapsed crater.
Borrowed from Spanish 'caldera', meaning 'cauldron'.