Final answer:
A caldera is a huge depression at the summit of a volcano produced by a collapse of the summit following a massive eruption.
Step-by-step explanation:
The depression at the summit of a volcano, produced by a collapse of the summit following a massive eruption, is called a caldera.
Calderas are formed when the magma chamber of a volcano empties during an eruption, causing the ground to collapse and create a large, bowl-shaped depression. This can be caused by the release of volcanic gases or the removal of magma from beneath the volcano. Calderas can be several kilometers in diameter and are often filled with water to form crater lakes, like the one at Mount Pinatubo in the Philippines.
Other examples of calderas include the Yellowstone Caldera in the United States and the Crater Lake Caldera in Oregon. Calderas are important features for understanding the eruptive history of a volcano and have significant geological and volcanic hazards implications.