NEARFIELD TSUNAMIS GENERATED BY THREE DIMENSIONAL BED MOTIONS

J.J. Lee, J.J. Chang

Abstract


A theoretical and computer simulation has been conducted on near field tsunamis generated by three dimensional bed motion. Linear dispersive wave theory has been used. Nonlinear effect has been found to be negligible for nearfield tsunami generation problem, as nonlinear effect is significant primarily for propagation over long distances. The specified bed deformation takes into account many possible dipole dislocation patterns with different aspect ratio. Three dimensional pictures of the water surface elevation were constructed from the array of computer data. For the nearfield tsunamis problem, the distance between the generation area and the shoreline is relatively short, thus the main generated wave quickly interact with the reflected leading wave from the coastal boundary to create an even more complicated wave profile. The coastal boundary can either focus on diffuse these waves, resulting in large variations in wave amplitude in the coastal region.

Keywords


tsunami; nearfield tsunami; bed motion; 3D bed motion

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