Calderas are large volcanic depressions, roughly circular in shape, from 1 to 250 km in diameter. Structures less than 1 km diameter are termed maars, and those over 250 km volcanic depressions.
The 1968 eruption of Fernandina volcano in the Galapagos Islands resulted in about 300 m of caldera collapse. The volume of the collapse was over 100 times greater than the volume of lava erupted during the event.
Examples of Calderas
Krakatau (Indonesia), Batur (Indonesia), Deception Island (Antarctica), Ambrym (Vanuatu).