> What's the term for a large depression formed when a volcano erupts andcollapses?And the answer: a caldera. Photo by: FRANCOIS GOHIER / ARDEA / CATERS NEWSAccording to National Geographic[https://www.nationalgeographic.org/article/types-calderas/], during a volcaniceruption, magma that's in the magma chamber underneath the volcano is expelled,often forcefully. When the magma chamber empties, the support that the magma hadprovided inside the chamber disappears. As a result, the sides and top of thevolcano collapse inward.If you've ever been to Yellowstone National Park[https://www.nps.gov/yell/index.htm], Crater Lake[https://www.nps.gov/crla/index.htm], or Valles Caldera National Reserve[https://www.nps.gov/vall/index.htm], chances are you've laid eyes on thesemagnificent post-eruption formations. Thousands of years ago, violent eruptionsemptied volcanic chambers to create calderas, often deep depressions in aonce-solid rock foundation. Calderas can form lakes or other bodies of water, asthe bowl-shape promotes the collection of rainwater. In fact, Oregon's CraterLake – a caldera that formed after the eruption of Mt. Mazama thousands of yearsago – is now the deepest lake in the United States. While most calderas form after a dramatic explosion of lava, they can form fromless intense eruptions, too. Slower eruptions often occur in shield volcanoes,which tend to be flatter and more sloped. Over time, lava flows outward tocreate a series of nested calderas, as seen in the Kilauea Volcano[https://www.discovermagazine.com/planet-earth/klaueas-summit-collapsed-into-itself] in Hawai'i. Resurgent calderas also represent another post-volcanic structure on our Earth.These calderas are the largest of the bunch, and form after the widespreadcollapse of large magma chambers. Resurgent calderas are produced from thedestructive eruptions known as pyroclastic sheet flows. The Toba Caldera[https://volcano.si.edu/volcano.cfm?vn=261090] on the Indonesian island ofSumatra is the newest resurgent caldera, created roughly 74,000 years ago by thelargest volcanic eruption in the last 25 million years. Did you know?Earth isn't the only planet with calderas. Other planets, such as Venus andMars, have calderas atop shield volcanoes and on widespread lava plains. Evenour moon has calderas!