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As it is impossible to know in advance the magnitude, or rupture length, of the next earthquake, we simulate 4 possibilities: 1. The rupture terminates at the northern edge of the 1833 event, total length 210 km. 2. The earthquake re-ruptures the area that failed in 1797, length 330 km. 3. The event re-ruptures the regions that slipped in 1797 and 1833, length 630 km. 4. In a worst case scenario, the rupture propagates south past Enggano Island for a total length of 840 km. A further unknown is the slip distribution of the future event and hence for each rupture length we model about 25 different distributions. In total, then, we simulate about 100 possible earthquakes. For each simulated event, we calculate the sea-floor displacement and resultant tsunami. An example of the seafloor displacement and tsunami resulting from one simulated 630 km long earthquake is shown in Figure 2. Figure 2: Seafloor displacement (left) and tsunami along the coast of Sumatra (right) for one modelled earthquake. Note that the outer islands (e.g. Siberut) experience uplift in the event whereas the west coast of Sumatra drops by up to a meter. In this scenario, the maximum wave height is about 5 m with Padang, a city of 840,000 people, experiencing a 3 m high tsunami. The large variability in tsunami height along the coast line is largely controlled by local bathymetry. Our 100 simulations led to some remarkable results. The first is that initial peak of the tsunami comes ashore on the west coast of Sumatra approximately 33 minutes after the earthquake; regardless of the size of the earthquake. This is illustrated in Figure 3 where we show two very different simulated events yet the time series of the tsunamis are very similar. Our second major result is that, in the near-field, there is a one-to-one correspondence between the coastal displacement resulting from a particular earthquake and the maximum height of the tsunami triggered by it. This is shown in Figure 4 where we plot the wave height vs. coastal displacement at 3 locations. This result suggests that single measure of, for example, the displacement of a seawall in an earthquake could be used to predict the height of the tsunami peak that will arrive 33 minutes later. 22
Figure 3: A) Two of our 100 modelled earthquakes, one 330 km long the other 630 km. B) Tsunami height as a function of time at Padang. The vertical line on each diagram is the average arrival time of the first peak over all 100 simulations. Figure 4: Tsunami wave height vs. coastal displacement for 3 different locations in Sumatra. The correlation between the two is location specific and related to local bathymetry. 23
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Page 11 and 12: OVERSEAS COLLABORATION 2007 East Af
Page 13 and 14: 4.2 QUATERNARY SCIENCE Stone run (b
Page 15 and 16: 4.3 FRESHWATER SCIENCE Toxic metals
Page 17 and 18: A comparison of the sediment toxici
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environmental sciences research institute - University of Ulster

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