Krakatoa

Krakatoa
An early 19th century image of Krakatoa
Elevation:	813 m (2,667 feet)
Location:	Sunda Strait, Indonesia
Coordinates:	6°6′27″S, 105°25′3″E
Type:	Volcanic caldera
Age of rock:
Last eruption:	2001

Krakatoa ( Indonesian name: Krakatau) is a volcano near the Indonesian island of Rakata in the Sunda Strait. It has erupted repeatedly, massively and with disastrous consequences throughout recorded history. The best known of these events occurred in late August, 1883.

The 1883 eruption ejected more than six cubic miles (25 cubic kilometres) of rock, ash, and pumice [1], and generated the loudest sound ever historically recorded by human beings — the cataclysmic explosion was distinctly heard as far away as Perth in Australia, and the island of Rodrigues near Mauritius. Atmospheric shock waves reverberated around the world. Near Krakatoa, according to official records, 165 villages and towns were destroyed and 132 seriously damaged, 36,419 people died, and many thousands were injured by the eruption, mostly in the tsunami which followed the explosion.

The eruption destroyed two-thirds of the pre-existing island of Krakatoa. New eruptions at the volcano since 1927 have built a new island, called Anak Krakatau (child of Krakatoa).

Origin and spelling of the name

The earliest mention of the island in the Western world was on a map by Lucas Janszoon Waghenaer, who labelled the island "Pulo Carcata." ("Pulo" is a form of pulau, the Indonesian word for "island".) There are two spellings, Krakatoa and Krakatau, that are both acceptable. While "Krakatoa" is more common, Krakatau tends to be favored by Indonesians. The origin of the spelling Krakatoa is unclear, but may have been the result of a typographical error made in a British source reporting on the massive eruption of 1883. The colonial Dutch, however, used the spelling Krakatowa, probably to make the Dutch pronunciation more accurate.

Theories as to the origin of the Indonesian name Krakatau include:

• Onomatopoeia, imitating the noise made by white parrots that used to inhabit the island.
• From Sanskrit karka or karkata or karkataka, meaning "lobster" or "crab".
• From Malayan kelakatu, meaning "white-winged ant".

There exists a popular belief that Krakatau was the result of a linguistic error. According to legend, "Krakatau" was adopted when a visiting ship's captain asked a local inhabitant the island's name, and the latter replied "Kaga tau" — a Jakartan/Betawinese slang phrase meaning "I don't know". This story is largely discounted; it closely resembles famous linguistic myths about the origin of the word kangaroo and the name of the Yucatán Peninsula.

The name is spelled "Karata" on a map drawn prior to 1708.

Before 1883

Before the 1883 eruption, Krakatoa was made of three islands: Lang and Verlaten, which were edge remnants left from an ancient, very large caldera-forming eruption; and Krakatoa itself, which had three volcanoes: Rakata (823m), Perboewatan (122m), and Danan (445m).

The 1883 eruption

Prior to Krakatoa's massive eruption of 1883, the volcano lay dormant for two centuries. In the years preceding the event, seismic activity around the volcano was intense, with some earthquakes felt as far distant as Australia. Beginning 20 May 1883, three months before the final explosion, steam venting began to occur on a regular basis.

By early August, three vents were regularly erupting on Krakatoa; tides in the vicinity were unusually high, and ships at anchor were moored with chains as a result. 11 August saw the onset of larger eruptions, with ashy plumes being emitted from as many as eleven vents. On 24 August, eruptions further intensified, and the cataclysmic phase began on Sunday 26 August, near midday. Ash clouds from the eruption reached a height of 36 km, and the first tsunamis were generated.

The 27 August eruptions occurred at 5:30 a.m., 6:42 a.m., 8:20 a.m., and 10:02 a.m. local time. The last of these eruptions opened fissures in the walls of the volcano, allowing sea water to flood the subterranean magma chamber. The resulting phreatic eruption of superheated steam all but annihilated Krakatoa, leaving only the southern tip ( Rakata). The blast was heard as far distant as the island of Rodrigues, near Mauritius, 4,800 km away; the sound of Krakatoa's destruction is believed to be the loudest sound in recorded history, reaching levels of 180 dBSPL 100 miles (160 km) away. After the largest explosion, there were several smaller ones through the day (some which nevertheless were heard as far as Sri Lanka) but generally declining in volume. By 28 August, Krakatoa was quiet again. Ash clouds caused by the eruption blocked sunlight for a couple of days within the area.

Pyroclastic flows, volcanic ashes and the tsunamis generated by explosion had disastrous results. There were no survivors from 3,000 people located at island of Sebesi, about 13 km from Krakatoa. Pyroclastic flows killed around 1000 people at Ketimbang, located on the coast of Sumatra some 40 km north from Krakatoa. Official death toll by Dutch authorities was 36,417 and many settlements destroyed, including Teluk Betung and Ketimbang in Sumatra, and Sirik and Semarang in Java. The areas of Bantam on Java and the Lampongs on Sumatra were devastated. Ships as far away as South Africa rocked as tsunamis hit them, and the bodies of victims were found floating in the ocean for weeks after the event. There are numerous documented reports of groups of human skeletons floating across the Indian Ocean on rafts of volcanic pumice and washing up on the east coast of Africa, up to a year after the eruption. Some land on Java was never repopulated; instead, it reverted to jungle and is now the Ujung Kulon National Park.

The 1883 eruption of Krakatoa is among the most violent volcanic events in modern times (a VEI of 6, equivalent to 200 megatons of TNT - about thirteen thousand times the yield of the Little Boy bomb which devastated Hiroshima, Japan (which was officially recorded as only 15 kilotons). In contrast, the biggest bomb ever exploded by man, the Tsar Bomba, had an explosive power of 57 megatons.) Concussive air waves from the explosions travelled seven times around the world, and the sky was darkened for days afterwards. The surrounding ocean floor was drastically altered. The land masses of Verlaten and Lang were increased, and volcanic ash continues to be a significant part of the geological composition of these islands. Polish Hat disappeared. A new rock islet called Bootsmansrots was left: it is a fragment of Danan. Two nearby sandbanks (called Steers and Calmeyer) were built up into islands by ashfall, but the sea later washed them away.

It should be noted that there exists an alternative theory for the final explosion: Overpressurization of the magma chamber. Some evidence suggests that Krakatoa's magma chamber may have been infused with newer, hotter magma, during the course of the event; as a result, the hotter magma may have expelled gas dissolved within the cooler magma and created an unsustainable level of pressure, leading to a cataclysmic explosion. Evidence for this theory is the existence of pumice consisting of light and dark material, the dark material being of much hotter origin.

Long-term effects

The eruption produced erratic weather and spectacular sunsets throughout the world for many months afterwards, as a result of sunlight reflected from suspended dust particles ejected by the volcano high into Earth's atmosphere. This worldwide volcanic dust veil acted as a solar radiation filter, reducing the amount of sunlight reaching the surface of the earth. In the year following the eruption, global temperatures were lowered by as much as 1.2 degrees Celsius on average. Weather patterns continued to be chaotic for years, and temperatures did not return to normal until 1888. British artist William Ashcroft made thousands of colour sketches of the red sunsets half-way around the world from Krakatoa in the years after the eruption. In 2004, researchers proposed the idea that the blood-red sky shown in Edvard Munch's famous 1893 painting The Scream is also an accurate depiction of the sky over Norway after the eruption.

Earlier eruptions

The shape of the island group shows that an originally circular island was broken up by an earlier (probably prehistoric) big caldera-forming eruption, about 60,000 years ago.

The Javanese Book of Kings records that in the year 338 Saka (= 416 AD) "A thundering sound was heard from the mountain Batuwara. [perhaps = Pulosari] There was a similar noise from Kapi, west of Bantam [= the north end of Java]. From it a great sheet of fire reached the sky. The whole world was shaken with violent thunderings that were accompanied by heavy rains of stones. The noise was fearful. With a tremendous roar Kapi burst into pieces and sank into the depths of the earth. The sea rose and inundated the land; its inhabitants drowned. The water subsided but the land on which Kapi stood became sea, and Java and Sumatra were divided into two parts." There is no geological evidence of a Krakatoa eruption of this size around that time; it may describe loss of land that previously joined Java to Sumatra across what is now the narrow east end of the Sunda Strait, or it may be a mistaken date, and actually refers to an eruption in 535 AD, for which there is geological evidence.

David Keys and others have postulated that a previous, even more violent eruption of Krakatoa may have been responsible for the global climate changes of 535-536. Additionally, in recent times, it has been argued that it was this eruption which created the islands of Verlaten and Lang (remnants of the original) and the beginnings of Rakata — all indicators of early Krakatoa's caldera size. However, there seems to be little, if any, datable charcoal from that eruption, even if there is plenty of circumstantial evidence.

There are reports that Danan and Perboewatan were seen erupting in May 1680 and February 1681.

Subsequent volcanism

Since the 1883 eruption, a new island volcano, called Anak Krakatau ("Child of Krakatoa"), has formed in the caldera. Of considerable interest to volcanologists, this has been the subject of extensive study since 1960. Additionally, it has also been a case study of island biogeography and founder populations in an ecosystem being built from the ground up, virtually sterilized, certainly with no macroscopic life surviving the explosion. The island is still active, with its most recent eruptive episode having begun in 1994. Since then, quiet periods of a few days have alternated with almost continuous eruptions, with occasional much larger explosions. Since the 1950s, the island has grown at an average rate of five inches (13 cm) per week. Reports in 2005 indicated that activity at Anak Krakatau was increasing.

Media

The volcano has inspired several books and films.

• The novel Krakatit ( 1924, ISBN 0685513386) by Czech writer Karel Čapek, dealing with lethal menace of a fictional explosive, was inspired by the name of the volcano.
• Krakatoa, a short 1933 movie about the volcano that won the Academy Award for Best Short Subject, Novelty for its producer Joe Rock. This movie was notable for overwhelming the sound systems of the cinemas of the time. In Australia, the distributors insisted on a power output of 10 watts RMS as a minimum for cinemas wishing to show the movie. This was then considered a large system, and forced many cinemas to upgrade.
• Krakatoa is the location of Professor William Waterman Sherman's adventures in the book The Twenty-One Balloons ( 1947, ISBN 0140320970) by William Pène du Bois, which won the Newbery Medal in 1948.
• In the TV series Time Tunnel, the episode "The Crack of Doom" aired on 14 October 1966.
• The eruption is the subject of a 1969 Hollywood film starring Maximilian Schell, which was titled Krakatoa, East of Java — even though Krakatoa is in fact west of Java. This blatant error is perhaps the most remembered thing about the film. ( Tambora, on Sumbawa, is the violent volcano east of Java).
• Simon Winchester explores the eruption of Krakatoa in his book Krakatoa: The Day the World Exploded, 27 August 1883. ( 2003, ISBN 0066212855). The book examines the history of the region, the early spice trade, the growth of colonial governments, explains the geology of volcanos and describes in detail the series of eruptions and tsunamis and their effects around the globe.
• The name of the living island Krakoa which battled the new X-Men called together by Professor X in Giant-Size X-Men #1 is obviously derived from the real Krakatoa.
• In the television series Doctor Who, the Third Doctor implied that he had heard the sound of the eruption — or possibly that of the creatures known as the Primords — sometime prior to the serial Inferno. In the episode Rose, a sketch dated 1883 was said to have washed ashore following the eruption; it showed the Ninth Doctor in front of the volcano.
• In Chapter 3 of Don Rosa's Life and Times of Scrooge McDuck, Scrooge McDuck rides out the tsunami from the eruption of Krakatoa.
• Ultimate Blast: Eruption at Krakatau [ sic] has been aired on Discovery Channel, as part of the Moments in Time series.
• In the Spongebob Squarepants episode "Mermaidman and Barnacleboy 5," Squidward is "Captain Magma". He says "Krakatoa" before lava spews out of the volcano shaped helmet.
• Fantasy author Graham Edwards' Stone trilogy (made up of Stone and Sky [1999], Stone and Sea [2000] and Stone and Sun [2001]) begins with the eruption of Krakatoa, which becomes the catalyst for the events that befall the main character Jonah Lightfoot and his companion Annie West. The force of the eruption blasts the two into a mysterious world called Amara. Volcanic eruption in general becomes a device later used when the eruption of Mount St. Helens in 1980 sends another person from our world into Amara.