This island is formed by the remaining edge of a large caldera that is submerged.
The northern one is the middle of the two, with a large caldera and a circular shape.
Within the large caldera there are at least five smaller collapse craters, up to 10 km in diameter.
The top of the volcano is a large caldera that host three crater lakes.
Its last major eruption took place around 1360, creating a large caldera.
Chacana is a large 32-km long - 18-24 km wide caldera that has erupted in historical times.
It lies within a larger caldera, which indicates that a very large eruption probably occurred thousands of years ago.
Historical unrest at large calderas of the world (1988)
It is inside a larger caldera Ijen, which is about 20 kilometers wide.
Two small shields or domes, several hundred meters high, occur within and adjacent to the large caldera.
