Shield volcano calderas do not result from singular explosive eruptions. They instead subside in gradualstages, due to the episodic release of lava. This less-explosive release of lava, known as lava fountaining, ischaracteristic of shield volcanoes. As a shield volcanoperiodically releases lava, it produces nested or terraced depressions rather than a large bowl-shaped caldera. As a result, shield volcano calderas are usually less than 5 kilometers (3.1 miles) in diameter. Composed of dormant and active shield volcanoes, the islands of Hawaii have a number of impressive shield volcano calderas. Moku'aweoweo, the caldera at the summit of Mauna Loa on the “Big Island” of Hawaii, is actually comprised of three distinct depressions that overlap. In total, the caldera complex has an area of roughly 15 square kilometers (6 square miles) and reaches a depth of 180 meters (600 feet).The Galápagos Islands are also a series of shield volcanoes with some summit calderas. Fernandina Island, the most volcanically active island in the chain, has a deepelliptical caldera that measures 4-by 6.5-kilometers (2.5-by 4-miles). In 1968, a massive volcanic eruption produced one of the largest caldera collapses in recent history. Like most shield volcano calderas, Fernandina caldera collapsed incrementally and asymmetrically, sinking in as much as 350 meters (1,150 feet) in some parts.