Krakatoa, also transcribed Krakatau, is a caldera in the Sunda Strait between the islands of Java and Sumatra in the Indonesian province of Lampung. The caldera is part of a volcanic island group comprising four islands. Two of them are known as Lang and Verlaten, another, Rakata, is the only remnant of an island mostly destroyed by an eruption in 1883 which created the caldera.
An 1888 lithograph of the 1883 eruption of Krakatoa
Simon Winchester maintains that the 1680 eruption was depicted in this eighteenth-century Dutch etching.
In 1780, crew members of HMS Discovery found the island as a friendly place whose vegetation was dense and lush; illustration by John Webber (1751–1793)
Large fan palm in the island; illustration by John Webber (1751–1793)
A caldera is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano 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. 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. Only seven caldera-forming collapses are known to have occurred between 1911 and 2016. More recently, a caldera collapse occurred at Kīlauea, Hawaii in 2018.
Landsat image of Lake Toba, on the island of Sumatra, Indonesia (100 km/62 mi long and 30 km/19 mi wide, one of the world's largest calderas). A resurgent dome formed the island of Samosir.
Valle Caldera, New Mexico
Satellite photograph of the summit caldera on Fernandina Island in the Galápagos archipelago
Oblique aerial photo of Nemrut Caldera, Van Lake, Eastern Turkey