Krakatau

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Krakatau
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History of Krakatau

• A long time ago Krakatau was one large island.
  Eruptions divided the island, splitting Krakatau
  into 3 parts in the form of a ring, called a
  caldera. The 3 islands are called Rakata,
  Sertung, and Panjang. The volcano started
  erupting again, building the main island, Rakata,
  in the center of the caldera. In May1883 Rakata
  began erupting again. There were small eruptions
  all summer, until August 26 when the eruptions
  started getting worse. Then one big explosion
  caused 2/3 of the island to collapse, or sink
  into the ocean on August 27, 1883.

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The Caldera Volcano

• 2/3 of Krakatau was destroyed in the 1883
  eruption. This happened because as the magma
  chamber emptied the outer walls failed and
  collapsed. This is also what happened in the
  eruption long ago. When the walls collapsed they
  created tsunamis, which killed 36,000 people on
  Java and Sumatra.

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Location

• Krakatau is located in southwestern Indonesia.
• It is in the Sunda Strait, between the islands of
  Java and Sumatra.
• Krakataus coordinates are 16.1 S and 105.4 E

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Krakatau Island

• This is a picture of the island now.
• The dotted line is an outline of what the island
  looked like before August 26, 1883.

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Before After
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Why Here?

• Krakatau is just 1 of the volcanoes in the
  Sunda Strait. The Sunda Strait is where the
  Australian plate and the Eurasian plate meet.
  Here the Australian plate is subducted under the
  Eurasian plate and as it descends the rock melts.
  Volcanoes are created where the magma rises
  through the crust. The volcano line running down
  the Sunda Strait (Java and Sumatra) changes
  abruptly at Krakatau. This is because the
  subduction of the crust is faster along the
  Sumatra trench than along the Java trench. It
  marks a major tectonic break and Krakatau marks
  a focal point in the bigger tectonic picture.

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Pictures
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Eruptions

• The biggest explosion of Krakatau occurred on
  August 26 and 27, 1883. Before the eruption the
  island was about 18 sq. miles. After the eruption
  the island was only 6 sq. miles. The eruption
  caused an earthquake which created tsunamis that
  reached more than 115 feet high and traveled some
  8000 miles. The waves killed about 36,000 people
  on the nearby islands of Java and Sumatra, and
  destroyed 295 costal towns. The explosions
  produced some of the loudest noises in history.

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Other Eruptions

• Before Krakataus 1883 eruption, the only
  previous recorded eruption of Krakatau was in
  1680.
• Krakatau was dormant after 1883, until 1927.
• In 1928, 22,358 earth tremors were registered on
  volcanic observatory on Panjang.
• A fourth island emerged in August 1930. By fall
  1932 the island was 47 meters high and 700
  meters in diameter.
• In November 1992, Krakatau erupted for 4 days.
  35,650 sq. meters were covered by lava that was
  about 5 meters thick.

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More Pictures
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Statistics

• Krakatau is about 300 meters high.
• Krakatau diameter is between 3 and 4 kilometers.
• Krakatau is a caldera volcano.
• Krakatau is an ejecta volcano which means it
  spews out ash and lava.
• Krakataus eruptions are explosive.
• Krakatau alternates between dormant and active.
  As of the mid 1990s it was active.
• Krakatau has a plinian eruption.

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Information

• Ash from the 1883 eruption was discharged 50
  miles high, and encircled the Earth within 2
  weeks.
• The island is uninhabited.

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Lava

• Krakataus lava type is aa (pronounced ah-ah).
  Its flow is usually thicker (about 3-5 meters),
  rougher, and red. One major chemical in the lava
  is silica (silicon and oxygen).

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Bibliography

• Encarta Encyclopedia Deluxe 2000
• Volcano World
• http//www.volcano.und.edu/
• Volcanoes of the World
• http//www.vulcan.wr.usgs.gov/Volcanoes/
  framework.html
• PBS Wild Indonesia
• http//www.pbs.org/wildindonesia/island/5.html

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Krakatau
The End
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