Finite element modeling of the July 12, 1993 Hokkaido Nansei-Oki tsunami

A fault plane model and a finite element hydrodynamic model are applied to the simulation of the Hokkaido Nansei-Oki tsunami of July 12, 1993. The joint performance of the models is assessed based on the overall ability to reproduce observed tsunami waveforms and to preserve mass and energy during tsunami propagation. While a number of observed characteristics of the waveforms are satisfactorily reproduced (in particular, amplitudes and arrival times at tidal gauges relatively close to the source, and general patterns of energy concentration), others are only marginally so (notably, wave periods at the same gauges, and wave heights along Okushiri); differences between observations and simulations are traceable to both the fault plane and the hydrodynamic models. Nonnegligible losses of energy occur throughout the simulated tsunami propagation. These losses seem to be due to a combination of factors, including numerical damping and possible deficiencies of the shallow water equations in preserving energy.