Assessing tsunami hazard in Sumatra: A Royal Society summer science exhibit

Despite the occurrence of two very large earthquakes (December 2004 and March 2005) in the Sumatra region, the seismic hazard in the area remains extremely high. Specifically, the Dec. and March events increased stress on the Sumatra fault, which runs down the centre of the island, and on the Sunda Trench south of the March rupture. The latter region, beneath the Mentawai Islands, is of particular concern because the last large earthquakes in the area were in 1797 near Siberut Island and in 1833 farther south. The 1833 earthquake is known to have caused a devastating tsunami.The Geophysics Group at the University of Ulster is now trying to model the range of possible tsunamis that could be generated by a large earthquake on the Sunda Trench beneath the Mentawai Islands. Because neither the rupture length or slip distribution of this forthcoming event can be known in advance, we are creating a range of possible synthetic earthquakes constrained by the best current understanding of the past earthquake history of the region. For each synthetic earthquake, we will calculate the seafloor displacement caused by it; this, in turn, will allow us to compute expected wave heights and energies. Based on these calculations, we will produce maps of likely, and worst case, tsunamis in the Indian Ocean.This work will be exhibited at the Royal Society's 2006 summer science exhibitions in London (July) and Glasgow (Sept.). Using interactive computer displays, users will be able to explore the tsunamic consequences of different potential earthquakes in the region. Information on earthquake hazard, as well as on earthquake and tsunami preparedness, will also be provided and members of the team will be on hand to discuss our work and its consequences.