Caldera

A caldera (/kɔːlˈdɛrə, kæl-/^[1] kawl-DERR-ə, kal-) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcanic eruption. An eruption that ejects large volumes of magma over a short period of time can cause significant detriment to the structural integrity of such a chamber, greatly diminishing its capacity to support its own roof, and any substrate or rock resting above. The ground surface then collapses into the emptied or partially emptied magma chamber, leaving a large depression at the surface (from one to dozens of kilometers in diameter).^[2] Although sometimes described as a crater, the feature is actually a type of sinkhole, as it is formed through subsidence and collapse rather than an explosion or impact. Compared to the thousands of volcanic eruptions that occur over the course of a century, the formation of a caldera is a rare event, occurring only a few times within a given window of 100 years.^[3] Only eight caldera-forming collapses are known to have occurred between 1911 and 2018,^[3] with a caldera collapse at Kīlauea, Hawaii in 2018.^[4] Volcanoes that have formed a caldera are sometimes described as "caldera volcanoes".^[5]