Krakatau in General
Indonesia is located between some world plates, like Indo-Australia plate, Eurasia plate, Pacific plate, and Philipine plate. That make Indonesia have a lot of volcanoes. In Sumatera, there are Kerinci, Marapi, and Sibayak. In Java, there are Merapi, Tangkuban Perahu, Merbabu, Kelud, and many more. In Nusa Tenggara, there are Kelimutu, Tambora, and Rinjani. And between Sumatera and Java, on the Sunda Strait, there is a little volcano, but very powerful.
It’s name is Krakatau. Krakatau, or spelled Cracatoa in English is a little island that have a little mountain (also named Krakatau or Rakata) and this mountain is still active until now. In 1883, Krakatau has erupted and that eruption was the biggest in the history.
Indonesia has over 130 active volcanoes, the most of any nation. They make up the axis of the Indonesian island arc system, which was 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 Straits, which are located at a bend in the axis of the island arc. Krakatau is located on this strait, between Java and Sumatera and that 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. Just imagine a triangle. If Krakatau is on that triangle, Krakatau is located on the top at that triangle, at the corner.
There are four theory about the origin of the name of this island. The first theory is the name was taken from the imitating voice made by “cockatoos”. But this theory is unlogic because cockatoos live in East Indonesia, like Papua or Maluku. The second theory, Krakatau was taken from Sanskrit name for lobster, karkata.Rakata also means crab in older Javan languge. The third theory, maybe Krakatau was taken from Malay word. The closest Malay word is kelakatu, meaning “white-winged ant”. Furneaux points out that in pre-1883 maps, Krakatau 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 nggak tau)—a Jakartan/Betawinese slang phrase meaning “I don’t know”.
Before the 1883 eruption, Krakatau comprised three main islands: Lang, Verlaten, which were edge remnants of a previous very large caldera-forming eruption, and Krakatau itself, an island 9 km long by 5 km wide. Also there was a tree-covered islet near Lang named Poolsche Hoed (“Polish Hat”, apparently because it looked like one from the sea) and several small rocks or banks between Krakatau and Verlaten. There were three volcanic cones on Krakatoa: Rakata, (820 m) to the south; Danan, (450 m) to the north; and Perboewatan, (120 m) to the north (Danan may have been a twin volcano). Look at the picture, as I said before, there is a theory said that Krakatau’s name maybe was taken from Malayan name for white winged ant. Is this picture like an ant?
Pre-1883 History
- 416 Event
The Javanese Book of Kings (Pustaka Raja Jawa) records that in the year 338 Saka (416 AD):
“…There was a sound of thunder that boomed from Mount Batuwara. There is also a frightening shock earth, total darkness, thunder and lightning. Then came the wind and rain storm and all the terrible storms, darken the whole world. A big flood came from Mount Batuwara and flows to east to Mount Kamula… When water drown it, the island of Java, separated into two, creating an island of Sumatra…”
But, there is no geological evidence for this eruption.
- 535 Event
The scientist said that in 535, Krakatau explode. They said that this explosion caused a global climate change. David Keys, Ken Wohletz, and others have postulated that a violent volcanic eruption, possibly of Krakatoa, in 535 may have been responsible for the global climate changes of 535-536. Keys explores what he believes to be the radical and far-ranging global effects of just such a putative 6th-century eruption in his book Catastrophe: An Investigation into the Origins of the Modern World. Additionally, in recent times, it has been argued that it was this eruption which created the islands of Verlaten, Lang, and the beginnings of Rakata—all indicators of early Krakatoa’s caldera’s size. To date, however, little datable charcoal from that eruption has been found. So, he said that this explosion separated ancient Krakatau island to be three main island.
The other scientist 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 850, 950, 1050, 1150, 1320, and 1530.
- 1680
In 1679, Dutch mining engineer, Johann Wilhem Vogel passed through Sunda Strait in his journey to Sumatera and saw that Krakatau Island was very beautiful, green, and healthy. But, when he returned to Java in 1681, he wrote in his diary :
“…I saw with amazement that the island of Cracketovv, on my first trip to Sumatra [June 1679] completely green and healthy with trees, lay completely burnt and barren in front of our eyes and that at four locations was throwing up large chunks of fire. And when I asked the ship’s Captain when the aforementioned island had erupted, he told me that this had happened in May 1680 … He showed me a piece of pumice as big as his fist.”
This diary told us that in 1681, there was an explosion of Krakatau. But we can not know how big the explosion was.
Explosion in 1883
The first activity happened in 1880. Mount Perbuatan producecd lava, but its not exploded. The vulcanic activity stop until 1883. In May 1883, Mount Rakata exploded. This explosion was not so big. But, this was an indication that this island active again and will explode someday. This activity didn’t stop until the big explosion in August.
That prediction was right. In August 27th 1883, Mount Rakata exploded. The explosion was very big and destructive. The blast was the biggest, loudest voice and the most devastating volcanic event in modern human history. Eruptive sound audible to 4600 km from the center of the eruption and can even be heard by 1/8 people of the earth at that time. The Guinness Book of Records recorded the explosion of Krakatau as the most powerful explosion in recorded history.
Krakatoa explosion had thrown rocks of volcanic pumice and ash with a volume of 18 cubic miles. The bursts of volcanic ash reaches 80 km. Hard objects are scattered into the air fell on the plains of Java and Sumatra, even to Sri Lanka, India, Pakistan, Australia and New Zealand. That was very amazing because as we now, the distance between Sumatera and New Zealand is very far. Krakatau explosive force equivalent to 200 megatons of TNT and 13,000 times greater than the Little Boy. Tsunami as high as 40 meters. Tsunami was also felt to Hawaii and the West Coast of America. After the explosion, the earth became dark because sunlight can’t penetrate the volcanic ash. Average global temperatures fell by as much as 1.2 degrees Celsius in the year following the eruption. Weather patterns continued to be chaotic for years and temperatures did not return to normal until 1888.
One hundred sixty five settlements disappeared. One hundred thirty two villages were destroyed. Mount Danan, Mount Perbuatan, and a half of Mount Rakata were destroyed. The official death toll recorded by the Dutch authorities was 36,417, although some sources put the estimate at more than 120,000. Mostly caused by the tsunami. 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.
Anak Krakatau
Fourty years after the eruption of Mount Rakata, actually in 1927, a volcano known as Anak Krakatau emerged. The eruptions were initially of pumice and ash, and that island and the two islands that followed were quickly eroded away by the sea. Eventually a fourth island named Anak Krakatau broke water in August 1930 and produced lava flows faster than the waves could erode them. Of considerable interest to volcanologists, this has been the subject of extensive study.
Every year it be higher around 20 feet and 40 feet wider. This is because the mountain still produces volcanic material, like pumice, ash, even lava. Today the height of Anak Krakatau reach about 300 meters above sea level, while Mount Krakatoa previously had 813 meters high above sea level.
Anak Krakatau has grown at an average rate of five inches (13 cm) per week since the 1950s. This equates to an average growth of 6.8 metres per year; the island is still active, with its most recent eruptive episode having begun in 1994. Quiet periods of a few days have alternated with almost continuous Strombolianeruptions since then, with occasional much larger explosions. The most recent eruption began in April 2008, when hot gases, rocks, and lava were released. Scientists monitoring the volcano have warned people to stay out of a 3 km zone around the island.
http://yoancosmos.wordpress.com/2010/05/16/the-legend-of-krakatau/
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