Krakatoa (), also transcribed (), 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 (Krakatoa archipelago) comprising four islands. Two of them are known as Lang and Verlaten; another, Rakata, is the only remnant of an island, also called Krakatoa, mostly destroyed by an eruption in 1883 which created the caldera.
In 1927, a fourth island, Anak Krakatoa, or "Child of Krakatoa", emerged from the caldera formed in 1883. There has been new eruptive activity since the late 20th century, with a large collapse causing the 2018 Sunda Strait tsunami. A new cinder cone eventually grew out of its collapse scar from eruptions in the 2020s.
Historical significance
The most notable eruptions of Krakatoa culminated in a series of massive explosions over 26–27 August 1883, which were among the most violent volcanic events in recorded history.
With an estimated volcanic explosivity index of 6, the eruption was equivalent to —about 13,000 times the nuclear yield of the Little Boy bomb (13 to 16 kt) dropped on Hiroshima, Japan, during World War II, and four times the yield of Tsar Bomba, the most powerful nuclear device ever detonated at 50 Mt.
The 1883 eruption ejected approximately of rock. The cataclysmic explosion was heard away in Alice Springs, Australia, and on the island of Rodrigues near Mauritius, to the west.
According to the official records of the Dutch East Indies colony, 165 villages and towns were destroyed near Krakatoa, and 132 were seriously damaged. At least 36,417 people died, and many more thousands were injured, mostly from the tsunamis that followed the explosion. The eruption destroyed two-thirds of the island of Krakatoa.
Eruptions in the area since 1927 have built a new island at the same location, named Anak Krakatau (which is Indonesian for "Child of Krakatoa"). Periodic eruptions have continued since, with recent eruptions in 2009, 2010, 2011, and 2012, and a major collapse in 2018. In late 2011, this island had a radius of roughly , and a highest point of about above sea level, growing each year. In 2017, the height of Anak Krakatau was reported as over above sea level; following a collapse in December 2018, the height was reduced to 110 meters (361 ft). The most recent eruption at Anak Krakatau took place in September 2026, beginning on 4 September 2026.
Etymology One of the earliest mentions of the name Krakatoa is in the Old Sundanese text Bujangga Manik, which was probably written in western Java in the late 15th century. Here Krakatoa is referred to as "the island of Rakata, a mountain in the middle of the sea" (pulo Rakata gunung ti tengah sagara, f. 27v). Although there are earlier descriptions in European sources of an island in the Sunda Strait with a "pointed mountain", the earliest mention of Krakatoa by name in the western world was on a 1611 map by Lucas Janszoon Waghenaer, who labelled the island "Pulo Carcata" (pulo is the Sundanese word for "island"). About two dozen variants have been found, including Crackatouw, Cracatoa, and Krakatao (in an older Portuguese-based spelling). The first known appearance of the spelling Krakatau was by Wouter Schouten, who passed by "the high tree-covered island of Krakatau" in October 1658.
The origin of the Indonesian name Krakatau is uncertain. The main theories are: From Sanskrit karka or karkaṭa or karkaṭaka, meaning "lobster" or "crab". The abbreviated form rakaṭa also means "crab" in the Old Javanese language. The fact that the earliest recorded mentions of the word closely resemble the pronunciation of these words for crab (rakata in Bujangga Manik and carcata in Waghenaer's map) makes this Sanskrit etymology the most likely origin of the word. Onomatopoeia, imitating the noise made by cockatoos (Kakatoes) which used to inhabit the island. However, Van den Berg points out that these birds are found only in the "eastern part of the archipelago" (meaning the Lesser Sundas, east of Java, on the other side of the Wallace Line). The closest Malay word is kelakatu, meaning "white-winged ant". Furneaux points out that in pre-1883 maps, Krakatoa does somewhat resemble an ant seen from above, with Lang and Verlaten lying to the sides like wings. Van den Berg (1884) recites a story that Krakatau was the result of a linguistic error. According to the legend, a visiting ship's captain asked a local inhabitant the island's name, and the latter replied, "Kaga tau" (Aku enggak tahu)—a Jakartan/Betawinese slang phrase meaning "I don't know". This story is largely discounted; it closely resembles other linguistic myths about the origin of the word kangaroo and the name of the Yucatán Peninsula.
The Smithsonian Institution's Global Volcanism Program cites the Indonesian name, Krakatau, as the correct name, but says that Krakatoa is often employed.Note: This spelling has been attributed to a sub-editor at The Times (who may have typographically swapped the 'a' and 'o' of the Portuguese spelling) interpreting telegraphic reporting on the massive eruption of 1883.
Geographical setting
Indonesia has over 130 active volcanoes, the most of any nation. They make up the axis of the Indonesian island arc system produced by northeastward subduction of the Indo-Australian Plate. A majority of these volcanoes lie along Indonesia's two largest islands, Java and Sumatra. These two islands are separated by the Sunda Strait located at a bend in the axis of the island arc. Krakatau is directly above the subduction zone of the Eurasian Plate and the Indo-Australian Plate where the plate boundaries make a sharp change of direction, possibly resulting in an unusually weak crust in the region.
Pre-1883 history At some point in prehistory, an earlier caldera-forming eruption had occurred, leaving as remnants the islands of Verlaten (or Sertung); Lang (also known as Rakata Kecil, or Panjang); Poolsche Hoed ("Polish Hat");Note: apparently because it looked like a hat from the sea and the base of Rakata. Later, at least two more cones (Perboewatan and Danan) formed and eventually joined with Rakata, forming the main island of Krakatoa.Note: The dating of these events is currently unknown. The Sunda Strait was first mentioned by Arab sailors circa 1100. At the time of the 1883 eruption, the Krakatoa group comprised Lang, Verlaten, and Krakatoa itself, an island long by wide. There were also the tree-covered islet near Lang (Poolsche Hoed) and several small rocky islets or banks between Krakatoa and Verlaten.
There were three volcanic cones on Krakatoa Island: Rakata, () to the south; Danan, () near the center; and Perboewatan, () to the north.
AD 416 event The Javanese (Pustaka Raja), a 19th-century compilation of historical traditions from Central Java, records that in the year 338 Śaka (416 AD):
The Pustaka Raja does not draw on primary sources for its description of this event, and its historical reliability is highly dubious. It is therefore impossible to verify its description of this eruption. There is no geological evidence presented that substantiates this eruption. David Keys, Ken Wohletz, and others have postulated that a violent volcanic eruption, possibly of Krakatoa, in 535 was responsible for the global climate changes of 535–536. Drilling projects in Sunda Strait ruled out any possibility that an eruption took place in 535 AD.
Middle Ages Ian Thornton mentions that Krakatoa was known as "The Fire Mountain" during Java's Sailendra dynasty, with records of seven eruptive events between the 9th and 16th centuries. These have been tentatively dated as having occurred in 850, 950, 1050, 1150, 1320, and 1530.
1680
In February 1681, Johann Wilhelm Vogel, a Dutch mining engineer at Salida, Sumatra (near Padang), on his way to Batavia (now Jakarta) passed through the Sunda Strait. In his diary he wrote:
Vogel spent several months in Batavia, returning to Sumatra in November 1681. On the same ship were several other Dutch travellers, including Elias Hesse, a writer. Hesse's journal reports:
The eruption was also reported by a Bengali sea captain, who wrote of the event later, but had not recorded it at the time in the ship's log. Neither Vogel nor Hesse mention Krakatoa in any real detail in their other passages, and no other travellers at the time mention an eruption or evidence of one. (In November 1681, a pepper crop was being offered for sale by inhabitants.)Note: Historians Van den Berg and Verbeek both conclude that Vogel must have exaggerated the extent of the eruption he saw. Even so, there must have been an eruption around this time.
Simon Winchester maintains, in his 2003 book Krakatoa: The Day the World Exploded: August 27, 1883, that the 1680 eruption was depicted in an eighteenth-century etching by Dutch cartographer Jan van Schley called Het Brandende Eiland, "The Burning Island", writing that "it was a depiction, without a doubt, of the otherwise little-chronicled eruption that supposedly took place in 1680."
In 1880, Verbeek investigated a fresh unweathered lava flow at the northern coast of Perboewatan, which he claimed could not have been more than two centuries old. From p. 164: "Over de gesteenten, waaruit de kegels Danan en Perboewatan bestonden, […] dat zij van de eruptie van 1680 afkomstig is." French translation: From p. 171: "Au suject des roches qui composaient les cônes Danan et Perboewatan, […] et permet de supposer qu'elle date de l'eruption de 1680." (On the subject of the rocks which composed the cones of Danan and Perboewatan, we possess only very little data. In the month of July 1880, I collected only samples of the flow of lava which, at the northern extremity of Perboewatan, were thrown into the sea. This flow still did not present any trace of degradation by atmospheric agents and was therefore entirely bare, thus contrasting with all of the rest of the island of Krakatau, which was covered by a thin layer of vegetation; this fact denotes the relatively young age of the lava in question and permits one to suppose that it dates from the eruption of 1680.)
Visit by HMS Discovery In February 1780, the crews of and , on the way home after Captain James Cook's death in Hawaii, stopped for a few days on Krakatoa. They found a freshwater and a hot spring on the island. They described the natives who then lived on the island as "friendly" and made several sketches. (In his journal, John Ledyard calls the island "Cocoterra".)
Visit by USS Peacock Edmund Roberts calls the island Crokatoa in his journal. A paraphrased account follows:
On 8 September 1832, US sloop-of-war Peacock anchored off the north end, also visiting Lang Island, in search of inhabitants, fresh water and yams. It was found difficult to land anywhere, due to a heavy surf and to the coral having extended itself to a considerable distance from the shore. Hot springs boiling furiously up, through many fathoms of water, were found on the eastern side of Krakatoa, from the shore. Roberts, Captain Geisinger, and marine lieutenant Fowler visited Forsaken island, having mistaken the singing of locusts for the sound of running water. The boat glided over crystal clear water, over an extensive and highly beautiful submarine garden. Corals of every shape and hue were there, some resembling sunflowers and mushrooms, others cabbages from in diameter, while a third type bore a striking likeness to the rose. The hillsides were typical of tropical climate; large flocks of parrots, monkeys in great variety, wild-mango and orange groves—a superb scene of plants and flowers of every description, glowing in vivid tints of purple, red, blue, brown, and green—but not water or provisions.
Dutch activity