NANO Posted April 10, 2019 Share Posted April 10, 2019 Scientists have produced a new model to illustrate the December collapse of Indonesia's Anak Krakatau volcano and its subsequent tsunami. The results indicate that 0.2-0.4 cu km of material on the southwestern flank of the volcano must have slid into the sea to produce the destructive waves. The simulation matches well the high-water readings recorded at tide gauges on Sumatran and Javan coasts. More than 400 people lost their lives in the disaster; 33,000 were displaced. The event took nearly everyone by surprise. The dangers of a landslide-generated tsunami stemming from a volcanic eruption had been under-appreciated. Local po[CENSORED]tions certainly had no warning. Scientists, also, were having to catch up, said Prof David Tappin, who presented the new model here at the European Geosciences Union General Assembly. Thinking had been strongly focused on the tsunamis from big earthquakes, the British Geological Survey and University College London scientist told reporters. "Why is Anak Krakatau interesting? Because it's the first such event we've been able to investigate using all the modern technologies and understandings that have come about over the past 20 years," he explained. "These include numerical tsunami modelling, particularly from non-seismic sources; satellite radar; high-resolution satellite photography before and after the event; and high-resolution seabed mapping.".Anak Krakatau's collapse occurred on the evening of 22 December, during a period of renewed eruptive activity. A number of factors are thought to have precipitated what happened, including the height (340m), steepness and inherent weakness of the volcanic structure; and the fact that it had grown up close to - and had even migrated towards - the edge of a deep (220m) submarine trough. When the flank went into the sea, it would have pushed out a big wave in front of it and sucked down the water surface immediately behind. The model shows how the disturbance spread out across the Sunda Strait. Prof Stephan Grilli, who led the modelling work at the University of Rhode Island, commented: "Numerical modelling of eruption-generated tsunamis is far less developed than for other tsunami mechanisms – such as earthquakes and landslides. "The Anak Krakatau event is timely in that it should stimulate the development of new models that will underpin improved mitigation strategies." Link to comment Share on other sites More sharing options...
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