GENERATION MECHANISM OF TSUNAMIS FROM THE 1883 KRAKATAU ERUPTION

The 1883 eruption of Krakatau generated a destructive tsunami which claimed about 34,000 lives. We compute the generation and propagation of tsunamis from three models previously proposed. They are 1) large-scale caldera collapse of the northern part of Krakatau Island; 2) emplacement of pyroclastic flow deposits; 3) submarine explosion. We numerically solve the non-linear shallow water equations on actual bathymetry. All three models displace the same volume (11.5 km3) of water in different ways. We compare the results of our computation with the observed tsunami waveforms at Batavia and tsunami wave heights along the coasts of Java and Sumatra. The comparison shows that the submarine explosion model of 1 to 5 min duration best explains the generation of the largest tsunami.