what is a caldera

A caldera is a large depression that forms when a volcano erupts and collapses. It is a type of volcano that is characterized by a large, usually circular volcanic depression formed when magma is withdrawn or erupted from a shallow underground magma reservoir. Calderas are excavational (or inverse) volcanoes with relief below the general land surface because they form from subsidence (or foundering) of the surface. They are the opposite of constructional volcanoes like cinder cones, composite volcanoes, and shield volcanoes that form from the accumulation of lava and tephra. There are two types of calderas: explosive and non-explosive. Explosive calderas are formed by large explosive eruptions that empty the magma chamber and cause the ground above it to collapse. Non-explosive calderas are located at the summit of most large shield volcanoes. The term "caldera" comes from Spanish "caldera" and Latin "caldaria," meaning "cooking pot".