To reduce future tsunami hazards, tsunami simulations for possible future events in the Mentawai region, especially the Padang area, based on dispersive wave equations (DSP) and non-dispersive wave equations, namely liner long-wave (LLW) and non-linear long-wave (NLLW), were conducted in this research. Through these simulations we attempted to estimate maximum tsunami height and tsunami arrival time for the Padang area assuming probable scenarios for future events. An additional objective was to understand which dispersive and non-linear terms affect the tsunami simulation results.
The simulation results were categorized into two parts. For deep water we compared DSP with LLW, and for shallow water, NLLW with LLW. From these comparisons we found that in deep water DSP almost similar with LLW; dispersive waves appear when a station is located perpendicular to the fault strike. Comparison of difference depth of 5, 10, and 20 km in the DSP simulations for scenario earthquake of Mw 8.5 shows that dispersive wave appears more clear at shallow depth. This indicates that dispersive wave may be useful for judging whether earthquake rupture reaches very shallow part near the trench or the rupture occurs only in deep part. In shallow water, advection and bottom friction terms should be considered when the depth is less than 50 m. Our simulations produced a maximum tsunami height in the Padang area of 0.91, 2.02 and 5.65 m for scenario earthquake of Mw 8.1, 8.5 and 8.9. The tsunami arrival times was 24, 20 and 17 min, for the scenarios of Mw 8.1, 8.5 and 8.9, respectively. In the Padang area tsunami countermeasures should be increased for the future earthquakes.