FINITE-ELEMENT MODELING OF THE JULY 12, 1993 HOKKAIDO-NANSEI-OKI TSUNAMI

A fault plane model and a finite element hydrodynamic model are applie d to the simulation of the Hokkaido Nansei-Oki tsunami of July 12, 199 3. The joint performance of the models is assessed based on the overal l ability to reproduce observed tsunami waveforms and to preserve mass and energy during tsunami propagation. While a number of observed cha racteristics of the waveforms are satisfactorily reproduced (in partic ular, 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 wav e heights along Okushiri); differences between observations and simula tions are traceable to both the fault plane and the hydrodynamic model s. Nonnegligible losses of energy occur throughout the simulated tsuna mi propagation. These losses seem to be due to a combination of factor s, including numerical damping and possible deficiencies of the shallo w water equations in preserving energy.