The Runup of a Tsunami (Seismic Sea Wave) on to a Shoreline

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The aim of this research program is to understand the runup of a tsunami on to a shoreline. When a tsunami (a long wavelength sea wave generated by an earthquake) encounters a coastline, severe damage may result due to flooding, to the flotation of large objects, and to the impact of the wave or floating objects with constructed facilities. The parameter that is important in evaluating the potential damage to a coastline is the wave runup. Very little useful scientific or engineering information exists on the runup of tsunamis. The objective of this study is to investigate some aspects of this complex phenomenon, beginning with the study of the runup of a cnoidal wave, which is one quintessential model for tsunamis. This investigation involves analytical modeling combined with laboratory experiments in a new 100 foot long wave tank. By comparing the results from these two approaches with results from numerical simulations of the Boussinesq equations, an attempt is made to determine the relative effects of dispersion, nonlinearity, and possibly dissipation, leading to more concise information on the validity of different models. This is followed by a preliminary laboratory investigation to determine the forces associated with cnoidal wave motion on simple structures, such as cylinders and plane surfaces, close to the shoreline. Potential applications of these fundamental studies to tsunami engineering are in the calibration of numerical models which are frequently used in evaluating the flooding of coastline areas prone to tsunami damage, and in the operation of tsunami early-warning systems.