A caldera is a large, basin-shaped volcanic depression that forms when a volcano collapses after the emptying of a magma chamber during an explosive eruption. Calderas are much larger than typical volcanic craters, often several kilometers in diameter. They are significant in understanding volcanic processes, the dynamics of magma chambers, and the potential hazards associated with large-scale eruptions.
Reference: Lipman, P. W. (1997). “Subsidence of Ash-Flow Calderas: Relation to Caldera Size and Magma-Chamber Geometry.” Bulletin of Volcanology, 59(3), 198-218.