What is a caldera?

A caldera is created when a volcano erupts so violently that it drains a huge volume of magma from the chamber beneath it, leaving the ground above unsupported so it collapses inward. The result is a broad basin that can be many kilometres across, far larger than an ordinary volcanic crater. Over time, calderas often fill with water to form lakes or host smaller new volcanic cones. Some of the largest calderas, known as supervolcanoes, formed in eruptions thousands of times more powerful than typical volcanic events. Famous examples include Crater Lake in Oregon and the vast Yellowstone caldera in the United States.