Application of a finite difference computational model to the simulation of earthquake generated tsunamis

Tsunamis are long waves and commonly modeled with the shallow-water wave approximation of the equations of motion. The calculation of tsunami inundation remains after two decades of progress a vexing and temperamental computation exquisitely dependent on ad-hoc algorithms. We present computed results using, a splitting method in space to reduce this hyperbolic system in two successive hyperbolic systems, one for each primitive variable. Then, we use dispersive, Godunov type finite difference method and solve the equations in characteristic form. We use the methodology implemented in the code MOST to calculate inundation from four different earthquake scenarios for Heraklion, Greece. MOST has been repeatedly benchmarked. The scenarios are geophysical estimates of the source mechanisms of the 365 AD event, the largest known earthquake in the Eastern Mediterranean in the last two millenia. The earthquake scenarios used allow for defining the seafloor deformation resulting from the parent seismic motions and, after translating them to the water surface, they constitute the initial conditions for computations. We use high resolution bathymetric and topographic data to generate fine resolution grids used in the computations. Our practice allows for a precise identification of the onland inundation and the overland flow depths and currents during tsunami flooding in Heraklion. This is the first time such a quantitative study has been undertaken for Eastern Crete. We conclude that there is substantial hazard, and there is little difference among the four different seismic interpretations of the 365 AD earthquake.