Caldera basin

A broad volcanic depression formed when a volcano’s summit collapses as magma drains from an underlying reservoir. Its floor may later host lava flows, lakes, or renewed volcanic activity.

Magma chamber: A subsurface region where molten rock accumulates within Earth’s crust. Withdrawal from this reservoir removes support beneath the summit.
Volcano: An opening in Earth’s crust through which magma, gases, and volcanic products reach the surface. A caldera basin is a collapse feature formed in a volcanic system.
Yellowstone Caldera: A large volcanic caldera in northwestern Wyoming associated with the Yellowstone hotspot. Its broad basin and later uplift illustrate a long-lived caldera system.
Maar: A broad, low-rimmed volcanic crater formed mainly by explosive interaction between magma and groundwater. A maar is excavated by explosions rather than formed by summit collapse.
Roof collapse: The downward failure of rock over a subsurface cavity or reservoir. This structural failure lowers the volcanic summit into a depression.
Magma: Molten or partially molten rock beneath Earth’s surface, commonly containing dissolved gases and crystals. Its movement and withdrawal drive the subsidence that forms a basin.
Crater Lake: A deep lake occupying the caldera of Mount Mazama in Oregon. It shows how water can fill a collapsed volcanic basin.
Pit crater: A steep-sided volcanic depression formed when the ground collapses above a void or drained magma pathway. Pit craters are typically smaller and more localized than caldera basins.
Ring fault: A roughly circular fault bounding a subsiding block of rock. Such faults can outline the block that sinks to form a basin.
Crater: A bowl-shaped volcanic depression, usually formed by excavation during an eruption or around a vent. A caldera is generally much broader and forms mainly through collapse.

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