8 - Krakatau, Sunda Strait

Summary

In 1883 the 7-km-long, 800-m-high island of Krakatau, in Sunda Strait, Indonesia (Fig. 8.1), erupted explosively with the force of more than 10,000 Hiroshima-type atomic bombs. Two-thirds of the island, including the two volcanoes that were active and half of the third and highest volcano, Rakata, now being unsupported, slumped into the emptied magma chamber, forming a 200-m-deep submerged caldera.

The remaining third of Krakatau, comprising half of the Rakata volcano, now known as Rakata Island, and the two closely adjacent islands, Sertung and Panjang (Fig. 3.3, p. 38), were covered in a blanket of hot ash some 30 m thick, thicker in places, which it is believed extirpated the animals and plants, thus setting in train a long-running, large-scale, ‘natural experiment’ in biotic colonization. The Krakataus are some 44 and 35 km from the biologically rich islands of Java and Sumatra, respectively, and the over-sea dispersal and recolonization of these islands by animals and plants, the course of the primary succession that followed, and the assembly of a new tropical forest community have been studied over the ensuing 110 years, with variable regularity and intensity (see, for example, Docters van Leeuwen 1936, Dammerman 1948, Tagawa et al. 1985, Whittaker et al. 1989, Thornton et al. 1990b, Thornton 1992a, 1996a, 1996b).

Monitoring of the reassembly of a flora on the three islands began in 1886 (Treub 1888) and continued fairly regularly until the 1930s (Docters van Leeuwen 1936).