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Case Study 11
Krakatau, Indonesia
A Volcano with a History
Malcolm Cooper
Introduction
Krakatau is a stratovolcano in the Sunda Strait
between the islands of Java and Sumatra in Indonesia
(Thornton, 1997; Figure CS11.1). The name is used
for the island group, the main island (also called
Rakata) and the volcano as a whole. Indonesia has
over 130 active volcanoes along the axis of the
Indonesian island arc system, which are produced by
north-eastward subduction of the Indo-Australian
Plate. Krakatau is located directly above the subduction
zone of the Eurasian Plate and the Indo-Australian Figure CS11.1 NASA Earth Observatory Landsat picture
Plate where the plate boundaries make a sharp change of Krakatau Island area 18 May 1992
of direction, possibly resulting in an unusually weak Source: www.en.wikipedia.org/wiki/File:Landsat_krakatau_18may92_
crust in the region. The best-known eruption of cropped.jpg
Krakatau culminated in a series of massive explosions
on 26–27 August 1883, which was among the most the eruption or from the tsunamis that followed
violent volcanic events in modern recorded history the explosion, according to official records. The
and contributed to the island’s attraction for tourists. eruption destroyed two-thirds of the island of
Krakatau. In the year following the eruption,
Geophysical aspects and average global temperatures fell by as much as
history of activity 1.2 degrees Celsius, and weather patterns continued
to be inconsistent for years, with temperatures not
The first massive explosion from the Krakatau returning to more normal levels until 1888.
volcano in 1883 (others were in AD535 and the Eruptions at the volcano since 1927 have built a
Holocene) with a VEI of 6, ejected approximately new island in the same location, named Anak Krakatau
3
21km of rock, ash and pumice (Simkin and Fiske, (‘Child of Krakatau’). This island currently has a radius
1983). The explosion was distinctly heard as far of roughly 2km and a high point of 300m above sea
away as Perth in Western Australia (3110km, level, and is growing by 5m each year. According to
Furneaux, 1965). In the vicinity of Krakatau 165 some reports (SVE Volcano News, 2009) the explosive
villages and towns were destroyed and 132 activity at Krakatau has resumed from 22 August 2009
seriously damaged. At least 36,417 (official toll) with strong vulcanian-type eruptions from the
people died, and many thousands were injured by growing lava dome in the new crater.
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