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Eruption of the former Krakatau volcano in 1883 (lithograph from 1888)

Eruption of the former Krakatau volcano in 1883 ( lithograph from 1888)

height 813  m
location Sunda Strait , Indonesia
Coordinates 6 ° 6 '10 "  S , 105 ° 25' 23"  O Coordinates: 6 ° 6 '10 "  S , 105 ° 25' 23"  O
Krakatau (Indonesia)
Type volcano
Last eruption 2020

Krakatau (also Krakatoa ) is a volcano under the Krakatau archipelago in the Sunda Strait between the Indonesian islands of Sumatra and Java . The volcano erupted several times over the past centuries. The most famous eruption, in which the island of Krakatau (Rakata) was almost completely destroyed by a powerful phreatomagmatic eruption , occurred on August 27, 1883. The catastrophe and the tsunami that it triggered killed more than 36,000 people. At that time the island belonged to the Dutch East Indies . The currently active vent is the Anak Krakatau ( "Child of Krakatau" ), which has been growing out of the water in the center of the archipelago as a new island from the submarine caldera of the volcano since 1927 , although it collapsed in 2018 due to an eruption.

The name of the volcano

Sunda Strait , strait between Sumatra and Java, where Krakatau is located
Location of Krakatau on Sunda Street
Transformations of the archipelago

The oldest mentions of the volcanic island in the western world can be found on a map by Lucas Janszoon Waghenaer (around 1533 / 34–1605 / 06). He named the island Pulo Carcata . Pulo is obviously derived from pulau , an Indonesian or Malay word for island . The names in use today are Krakatoa or Krakatau. The name Krakatoa is widely used, especially in the English-speaking world; the term Krakatau, on the other hand, is often used by Indonesians.

Geological history

Krakatau is considered to be one of the most explosive and dangerous volcanoes. Its special explosive power is explained by two geological features. On the one hand through the geographical location of Krakatau, which, like all volcanoes in Indonesia, is part of subduction volcanism . Two tectonic plates collide there. The heavier Indo-Australian plate moves steadily under the lighter Burma plate, part of the Eurasian plate. Heavy seabed is pushed under lighter rocks on the continent. On the other hand, the subduction zone in the Krakatau area suddenly changes its course, creating large cracks in the earth's crust and additional geological tensions.

Early history

For early history there is the theory that there was a single, large island at the site of today's archipelago, the Proto-Krakatau . It is said to have exploded in AD 535. This breakout could have resulted in the 535/536 weather anomaly . Since this event at the latest, there has been an archipelago consisting of the islands of Sietet, Panjang and a large island called Krakatau with the three volcanic cones Perboewetan, Danan and Rakata.

The great eruption of 1883

The first documented sign of the impending and best-known eruption of Krakatau was on May 9, 1883: an earthquake just before midnight shook the region around the Vierde Punt lighthouse near Anger , which was closest to Krakatau. At that time, the high pressure in the Earth's interior burst the fault line directly below the volcano. Magma rose and tore the crust. That night, the lighthouse keeper observed how the water of the Sunda Strait appeared as smooth as glass for a moment, only to return to normal swell afterwards.

On May 20, 1883, the island of Krakatau, which consisted of the three cones Rakata (820 m), Danan (450 m) and Perboewatan (120 m), finally awoke from its volcanic dormant phase, which lasted over 200 years and in which the enormous explosion pressure had built up. This first eruption, which marked the beginning of much more powerful eruptions in the following period, came from the crater of Perboewatan.

Krakatau before the eruption, 19th century

Because of these first minor eruptions, the Dutch colonial administration sent two expeditions one after the other, the first of which returned when the damage was seen on the island, while the second - partially ignorant of the dangers - climbed the volcano again and, so to speak, was the last to climb the interior of the already active one , but briefly dormant volcano, before it disappeared a short time later in a huge caldera explosion .

The first eruption took place on Wednesday, August 22, 1883 . On Sunday, August 26th, at 1:06 p.m. (local time), another took place. The second eruption occurred on August 27, 1883 at 5:30 a.m., the third at 6:44 a.m. and another at 8:20 a.m. At 10:02 a.m. the most violent eruption took place. The bang of this final outbreak is considered to be the loudest sound man has ever heard and represents the longest range of a sound wave in the air. It was close to both Perth, 3,100 kilometers away, and Rodrigues Island, some 4,800 kilometers away Mauritius to hear. Atmospheric pressure waves were registered around the earth. The air pressure wave was still measurable after five days and seven orbits of the earth.

All three cones on the island were active at the same time. Krakatau hurled 18 to 20 km³ of ash and rock up to a height of 25 km into the earth's atmosphere . The eruption thus achieved the volcano explosion index VEI = 6.

The energy of the eruption was after 130 megatons and after between 200 and 2,000 megatons of TNT equivalent .

The explosions were so violent that the resulting fluctuations in air pressure caused window panes to tremble and objects in houses fell to the floor in Batavia (now Jakarta ), 130 km away .

The underground magma chamber emptied quickly and then collapsed under the weight of the ceiling formation, whereupon the water masses of the surrounding sea poured in. The collapse caused a tsunami up to 40 meters high in places on the surrounding coasts . The tidal wave was followed by ash rain and pyroclastic flows  - scorching hot mixtures of rock, gas and ash that can reach speeds of up to 400 km / h and temperatures of 300 to 800 ° C. They destroyed 165 cities and villages on the surrounding islands and killed a total of at least 36,417 people. Even a steamship was pushed four kilometers inland. It was the Dutch ship Berouw , which was anchored in the port of Telok-Betong. Two thirds of the volcanic island sank into the sea.

The Vierde Punte lighthouse near Anger was hit by a large block of coral that had been torn from the seabed and weighed around 600 tons. The tower broke and was washed into the sea. The two-meter-thick brick foundation of the old lighthouse and a monument are reminiscent of the natural disaster. The cone of the Perboewatan and the cone of the Danan disappeared completely in the eruption on August 27, 1883. About 50% of the cone of the Rakata, which today itself forms the rest of the island of Krakatau, remained.

After the eruption of the Samala in 1257 and the Tambora in 1815, the Krakatau eruption is one of the 6 largest volcanic eruptions of the last millennium. Its strength reached a volcanic explosion index of 6 (VEI, possible values ​​0 to 8). During the violent eruptions of Mount St. Helens in May 1980, the amount ejected was about 1 km³ and for Pinatubo 1991, also VEI 6, about 10 km³. The strongest eruption in the last 10,000 years was between April 10 and 15, 1815 that of Tambora on the Indonesian island of Sumbawa . This eruption had a VEI of 7 and hurled about 160 km³ of material into the atmosphere. No eruption reached a VEI of 8 in the last 10,000 years.

Effects worldwide

Volcanoes in Indonesia

The tidal wave was also registered in Europe . At levels in the Bay of Biscay 17,000 kilometers from its origin and along the English Channel it was recorded as a deflection of 2 cm.

Larger particles, such as pumice , which according to contemporary reports from European seafarers covered large areas of the sea in the vicinity, fell in an area of ​​almost 4 million km² - an area twice the size of the entire Indonesian archipelago . The fine volcanic ash and aerosols rose into the upper atmosphere and distributed there in over 70% of this air layer worldwide in just a few days.

Spectacular sunsets have been observed around the world due to the particles in the atmosphere that caused refraction. According to a study by American scientists, the striking reddish color of the sky in Edvard Munch's famous painting " The Scream " is said to be due to the changes in the color of the sky worldwide after the eruption. Munch wrote in his diary: "Suddenly the sky turned blood red, the clouds of blood and flames hung over the blue-black fjord and the city".

An astronomer reported to Nature about the total lunar eclipse on October 4, 1884 , that "... the darkening of the moon goes far beyond what has been seen in recent eclipses". Comparative photos were published in the astronomy journal Sirius in 1888 .

The turbidity index of the atmosphere introduced to characterize the consequences of volcanic eruptions was referenced at the Krakatau event and set to 1000 for this. Mainly due to the aerosols reflecting the sunlight, the average temperature in the northern hemisphere fell by approx. 0.5–0.8 ° C. It took several years for these particles to disappear from the atmosphere.

The Krakatau eruption in 1883 is cited in media studies as one of the earliest examples of the global village . Without the telegraphic reports to Europe, for example, the tidal wave would not have been recognized.

Wildlife and ecology

Rakata, 2013

The larger animal species did not survive the outbreak. In 1889 the remains of ancient volcanic cone Rakata by angeschwommene from neighboring islands were monitor lizards colonized. After the eruption, some expeditions were conducted to study the wildlife. In 1933, snakes , geckos and other small lizards as well as other small animals such as bats, birds and rats were discovered during such an expedition , most of which had reached the island through driftwood . Fifty years after the Krakatau explosion, in the early 1930s, the biological equilibrium was completely restored. Today Rakata is densely forested again.

Anak Krakatau

Anak Krakatau north of Krakatau Island (Rakata)
The second of the three temporary precursor islands of today's Anak Krakatau in May 1929. From the collection of the Amsterdam Tropical Museum
Volcanic activity of Anak Krakatau, 2008

After a long period of inactivity, the Anak Krakatau ( "Child of Krakatau" ) began to rise in 1927 exactly where the cone of Danan was then, as a new submarine volcanic building on the edge of the Krakatau caldera. Three ash cones broke through the water surface one after the other, each of which was destroyed by marine erosion and submarine landslides on the steep slope of the caldera. In August 1930 a fourth island was formed, which is still there today. Many of the people living in the region did not take the threat of Anak Krakatau eruption very seriously. Often they also lacked knowledge of what had happened in the past.

Between 1959 and 1963 the volcano was most active so far.

A major eruption of Anak Krakatau took place on November 8, 2007, without endangering people; in June 2009 the Anak Krakatau erupted again and has shown sustained strombolian activity ever since . This makes it one of the most active volcanoes on earth.

The most violent eruption of Anak Krakatau for over ten years took place on September 2nd and 3rd, 2012: cannon-like explosions occurred without interruption, releasing large quantities of pyroclastics . In addition, an approx. 600 meter long lava flow flowed from the summit region to the southeast and poured about 100 meters into the sea. Only on September 3, 2012 at around 4 p.m. did this violent eruptive phase turn into light strombolian activity.

Eruption of Anak Krakatau 2018

Anak Krakatau, 2019

A new eruption phase of Anak Krakatau began in mid-2018. On September 22nd, an increasing sequence of eruptions ( paroxysm ) occurred , during which thermal radiation of approx. 3400 megawatts and volcanic ash at an altitude of up to 2300 meters were measured.

Another major eruption of Anak Krakatau with a three kilometer high ash cloud took place on December 22, 2018 at 9:03 p.m. local time. About 24 minutes later, a tsunami flooded coastal regions on the Sunda Strait on the islands of Sumatra and Java . At least 429 people were killed and 1,485 injured, about 154 are missing. Beach resorts such as Pantai Tanjung Lesung on the coast of Banten province were also affected by the approximately three-meter-high wave . The high level of property damage was also caused by the spring tide prevailing at the time of the accident (it was a full moon), which increased the height of the rising water. The tsunami was triggered by an underwater landslide . A timely warning was therefore not possible; the warning systems react primarily to seaquakes . The Anak Krakatau has lost a lot of its substance in the most recent eruptions. Its height was reduced from 338  m to around 110  m ; it lost up to three quarters of its overseas volume. The currently active vent is under water. The type of eruption in the days after the tsunami had changed due to the interaction of lava with the sea water ( Surtseyan eruption type ), the danger from the volcano remained high, and the warning level was raised.

At the end of February 2019, the Center for Volcanology and Geological Hazard Mitigation issued a warning to fishermen in the region to keep a respectful distance of at least five kilometers from the mountain, which at that time still had a column of smoke about 500 meters high.

Eruption of Anak Krakatau 2020

Satellite image from April 17, 2020. The strong infrared signal shows considerable heat in the crater.

Anak Krakatau erupted again on April 10, 2020. The explosion could be heard in Jakarta, 150 km away. Damage was not known.


  • Wilfried Schröder: The Krakatau eruption a hundred years ago . In: Technical Information Library [TIB] (Ed.): Geosciences in our time . Verlag Chemie GmbH, Weinheim 1983, p. 155–159 , doi : 10.2312 / geosciences.1983.1.155 .
  • Arno Schmidt : Krakatau. Reclam, Stuttgart 1975, ISBN 3-15-009754-1 .
  • Simon Winchester: Krakatau. The day the world broke up; August 27, 1883 . 1st edition. Knaus, Munich 2003, ISBN 3-8135-0224-4 (English: Krakatoa - The Day The World Exploded: August 27, 1883. New York 2003. Translated by Harald Stadler).
  • The Krakatau Eruption In: Spectrum of Science . 1/1984.
  • The Scream In: Astronomy Today . 3/2004.
  • Ian Thornton : Krakatau: The Destruction and Reassembly of an Island Ecosystem , Harvard University Press (Cambridge, MA), 1996. ISBN 978-0-674-50572-8 .


See also

Web links

Photos and videos

Commons : Krakatau  - collection of images, videos and audio files

Scientific contributions


Individual evidence

  1. a b Krakatau in the Global Volcanism Program of the Smithsonian Institution (English)
  2. a b c Anak Krakatau spits lava and gas. In: Spiegel Online , November 8, 2007.
  3. The Dark Age - Did a massive volcanic eruption cause the cold spell in the 6th century? In: Image of Science. January 9, 2001, accessed September 8, 2019 .
  4. a b Anak Krakatau - powder keg in Sundastrasse, 2008, updated 2018.
  5. a b Reiselexikon Sunda Islands , accessed on October 12, 2018.
  6. a b Stefan Schmitt: Before an audience. In: ZEIT Online , accessed on October 12, 2018.
  7. Olson, Donald W .; Russell L. Doescher and Marilynn S. Olson (May 2004). "The Blood-Red Sky of the Scream". APS News (American Physical Society) 13 (5). Retrieved December 22, 2007.
  8. Sirius , Zeitschrift für popular Astronomie, 1888 (supplement table 11), cited in [1] , accessed on October 12, 2018, no longer available on December 26, 2018.
  9. Mark Szeglat: Volcanic Winter: Effects of Volcanic Eruptions on the Climate. In: , accessed on October 12, 2018.
  10. a b Wild Indonesia: Birth of an Island - The Child grows . Posted by Rob Whittaker on PBS . Last accessed on May 28, 2011
  13. Violent eruptive phase of Anak Krakatau on September 2nd and 3rd, 2012 Short report of the "Georesearch Volcanedo Germany"; On:
  14. Vulkane Net Newsblog: Anak Krakatau New Paroxysm , accessed on September 23, 2018.
  15. a b c Many dead from tsunami in Indonesia. In: . 23 December 2018.
  16. Even more deaths after the tsunami. In: December 25, 2018.
  17. Further eruptions of Anak Krakatau - fear of a new seaquake In: Die Welt . December 24, 2018.
  18. ^ Anak Krakatau New Paroxysm. In: Vulkane Net Newsblog . Retrieved December 23, 2018
  19. Dead after tsunami in Indonesia. In: MSN Nachrichten , accessed December 23, 2018.
  20. Arne Perras: The horror of Krakatau is back. In: Süddeutsche Zeitung . 23 December 2018.
  21. Holger Senzel: "Warning system reacts primarily to seaquakes". In: . 23 December 2018.
  22. Indonesian volcano Anak Krakatau strongly shrunk. Süddeutsche Zeitung , December 29, 2018, accessed on August 19, 2020 .
  23. Geographical Survey Institute of Japan from December 25, 2018: The 2018 Krakatau Eruption, Indonesia: Geomorphic change detected by ALOS-2 data
  24. Marguerite Afra Sapiie: Anak Krakatau's changing eruption pattern won't trigger tsunami , The Jakarta Post , December 27, 2018.
  25. Fisherfolk told to keep distance from active Anak Krakatau
  26. Eruption at Indonesian volcano Krakatoa