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A caldera is a cauldron-like volcanic feature on large central volcanoes, a special sort of volcanic crater (from one to several kilometers in diameter), formed when a magma chamber was emptied.The depression then originated either in very big explosive eruptions or in erosion and collapse of the magma chamber roof.f volcanic activity continues, the center of the caldera may be uplifted in the form of a resurgent dome such as is seen at Cerro Galan, GalÃ¡n Lake, Toba, yellowstone., etc by subsequent intrusion of. Magma a silicic or rhyolitic caldera may erupt hundreds or even thousands of cubic kilometers of material in a single. event
They are large volcanic craters that form by two different methods: 1) an explosive volcanic eruption; or, 2) collapse of surface rock into an empty magma chamber. The image at right is a satellite view of one of the most famous calderas-Crater Lake in Oregon.ruptions of ash and pumice: The cataclysmic eruption started from a vent on the northeast side of the volcano as a towering column of ash, with pyroclastic flows spreading to the northeast. Caldera collapse: As more magma was erupted, cracks opened up around the summit, which began to collapse.