Krakatoa

Krakatoa

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Krakatoa: The Last Days, Clip 1 – Tsunami

Krakatoa: The Last Days, Clip 2 – Ashes (HD)

Krakatoa: The Last Days, Clip 3 – Loudest Sound

Krakatoa: The Last Days, Clip 4 – The Wave (HD)

Krakatoa: The Last Days, Clip 5 – Lighthouse (HD)

Krakatoa: The Last Days, Clip 6 – Pyroclastic Surge

Krakatoa: The Last Days, Clip 7 – Aftermath

Krakatoa (Indonesian: Krakatau), also spelled Cracatoa or Krakatau, is a volcanic island made of  lava in the Sunda Strait between the islands of Java and Sumatra in Indonesia. The name is used for the island roup, the main island (also called Rakata), and the volcano as a whole.

The best-known eruption of Krakatua culminated in a series of massive explosions on August 26–27, 1883, which was among the most violent volcanic events in modern and recorded history.

With a Volcanic Explosivity Index (VEI) of 6, the eruption was equivalent to 200 megatons of TNT (840 PJ)—about 13,000 times the nuclear yield of the Little Boy bomb (13 to 16 kT) that devastated Hiroshima, Japan during World War II and four times the yield of the Tsar Bomba (50 MT), the largest nuclear device ever detonated.

The 1883 eruption ejected approximately 21 cubic kilometres (5.0 cu mi) of rock, ash, and pumice.[4]

The cataclysmic explosion was distinctly heard as far away as Perth in Western Australia, about 1,930 miles (3,110 km) away, and the island of Rodrigues near Mauritius, about 3,000 miles (5,000 km) away.[5]

Near Krakatau, according to official records, 165 villages and towns were destroyed and 132 seriously damaged, at least 36,417 (official toll) people died, and many thousands were injured by the eruption, mostly from the tsunamis that followed the explosion. The eruption destroyed two-thirds of the island of Krakatoa.

Eruptions at the volcano since 1927 have built a new island in the same location, named Anak Krakatau (Indonesian: “Child of Krakatoa”). This island currently has a radius of roughly 2 kilometres (1.2 mi) and a high point around 300 metres (980 ft) above sea level, growing 5 metres (16 ft) each year.

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535 AD event

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.[8] 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.

Thornton (p. 47) 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 (all AD).

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The 1883 eruption

While seismic activity around the volcano was intense in the years preceding the cataclysmic 1883 eruption, a series of lesser eruptions beginning in mid-June 1883 led up to the disaster. The volcano released huge plumes of steam and ash lasting until late August.

On August 27, a series of four huge explosions almost entirely destroyed the island. The explosions were so violent that they were heard 3,500 km (2,200 mi) away in Perth, Western Australia and the island of Rodrigues near Mauritius, 4,800 km (3,000 mi) away. The pressure wave from the final explosion was recorded on barographs around the world, which continued to register it up to 5 days after the explosion. The recordings show that the shockwave from the final explosion reverberated around the globe 7 times in total. Ash was propelled to a height of 80 km (50 mi).

The combined effects of pyroclastic flows, volcanic ashes, and tsunamis had disastrous results in the region. The official death toll recorded by the Dutch authorities was 36,417, although some sources put the estimate at more than 120,000. 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.

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.

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Subsequent volcanism - Anak Krakatau

 Verbeek, in his report on the eruption, predicted that any new activity would manifest itself in the region which had been between Perboewatan and Danan. This prediction came true on 29 December 1927, when evidence of a submarine eruption was seen in this area (an earlier event in the same area had been reported in June 1927). A new island volcano, named Anak Krakatau (“Child of Krakatoa”), rose above the waterline a few days later. 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.

Current activity

2004 Boxing Day Tsunami

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 Strombolian eruptions 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.

On 6 May 2009 the Volcanological Survey of Indonesia raised the eruption alert status of Anak Krakatau to Level Orange.

Clay Animation: Krakatoa Explosion

Krakatau Erupts!

Cracatoa / Krakatau Volcano- 10 Nov 2007

Anak Krakatoa in action.

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