Caldera

Mount Mazama's eruption timeline, an example of caldera formation

A caldera is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber/reservoir in a volcanic eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is lost. The ground surface then collapses downward into the emptied or partially emptied magma chamber, leaving a massive depression at the surface (from one to dozens of kilometers in diameter). 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. Only seven caldera-forming collapses are known to have occurred since 1900, most recently at Bárðarbunga volcano, Iceland in 2014.[1]

Etymology

The term caldera comes from Spanish caldera, and Latin caldaria, meaning "cooking pot". In some texts the English term cauldron is also used. The term caldera was introduced into the geological vocabulary by the German geologist Leopold von Buch when he published his memoirs of his 1815 visit to the Canary Islands,[note 1] where he first saw the Las Cañadas caldera on Tenerife, with Montaña Teide dominating the landscape, and then the Caldera de Taburiente on La Palma.