What is the term for a large depression formed when the summit of a volcano collapses or is blown away?

• A. Caldera
• B. Composite Volcano
• C. Epicenter
• D. Fault

Answer: (A)

Caldera is a large depression formed when the summit of a volcano collapses or is blown away. This happens after a major eruption or when much of the magma in a shallow chamber has drained away, causing the overlying rock to lose support and slump inward, creating a wide basin often several kilometers across. Over time, calderas may fill with water and become large crater lakes. By contrast, a composite volcano describes a volcano’s overall type and structure, not the depression left after collapse. An epicenter is the point on the surface directly above where an earthquake begins, and a fault is a fracture in rocks where movement occurs—neither term describes a collapsed summit.