Tsunami database in Bali and Nusa Tenggara regions, Indonesia has been created in this study. Two types of bathymetry grids were applied for tsunami simulations, namely finer mesh grid and coarse mesh grid. The intervals of finer and coarse mesh grids are 20 arc-second (~616.67 m) and one arc-minute (~1850 m), respectively. The 1977 Sumbawa earthquake was adopted as a real case study. We compared the simulation results from the both grids in order to investigate the effective way to create a tsunami database. The coarse mesh grid will be used for tsunami simulations of hypothetic earthquakes to construct the tsunami database. We located 21 source points (SP) along the trench axis, surrounding the real case of the 1977 Sumbawa earthquake, with three magnitudes (M 7.0, 7.5 and 8.0) and four depths (0, 20, 40 and 60 km) set for tsunami simulations, in total 252 hypothetic cases. We located 38 coastal points (CP) and 38 forecast points (FP) as target points. We estimated maximum tsunami heights at CPs by applying Green’s law to those at FPs. Inverse refraction diagram was used to obtain tsunami arrival times at CPs.
Three kinds of method to retrieve values from the database were applied in this study, namely interpolation methods for epicenter location, magnitude and depth; extrapolation methods for magnitude and depth; and maximum risk methods. Those methods are very useful to pick up data from the database, which are used for issuing tsunami warning. The comparison of tsunami heights from the direct simulation and the retrieved values from the database shows a good agreement for the real case.