Name：Takaya Kaneko

title：Generation and propagation of initial tsunami waveforms induced by submarine ground deformation

academic advisor：Tokuzo Hosoyamada

This study conducts tsunami numerical simulations using equations for long wave in nonlinear. The conventional model may be inaccurate because it represents the deformed shape of the seafloor and the deformation of the water surface with η = zb, which is given instantaneously. Therefore, the nonlinear long wave equation before approximation is compared with the conventional model as a dynamic analysis. To investigate the effect of seafloor deformation, five patterns of uplift and subsidence were prepared for the flat and slope models, respectively.
Compare static and dynamic analysis in a horizontal model tsunami simulation. The initial waveform is fixed at 1 m in the static analysis, but in the dynamic analysis, there are differences depending on the deformation shape, and in particular, the initial waveform is smaller for non-uniform deformation. Since the deformation rate is constant, the deformation ends earlier in areas with smaller deformation and enters the propagation phase. During the propagation process, the water surface gradient of the static analysis is larger than that of the dynamic analysis, and depending on the deformation shape, there is a 40% difference in the propagation water level, which is lower in the dynamic analysis. The arrival time after the start of ground deformation is earlier in the static analysis, and the initial water level, propagating water level, and arrival time may be overestimated compared to the dynamic analysis.
In slope model calculations, the focus was on deformation shape impact on uprush. Uniform uplift/subsidence showed the maximum uprush, with a 3m difference observed between half-ellipse and curve uplift. Static analysis tends to reach maximum uprush distance 20-30 seconds earlier than dynamic analysis, with significant differences based on deformation shape. Maximum uprush distance and height are larger in static analysis than dynamic, especially notable in half-ellipse uplift.
From the above, the static analysis has larger initial waveform, propagation process, and run-up height values than the dynamic analysis. The dynamic analysis is more advantageous in terms of its wider applicability.