introduction

the 1964 Alaska tsunami

three phases of tsunami evolution:
• generation
• propagation
• runup

the model and grids

references

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Tsunami runup is the final and most destructive phase of tsunami evolution. The hydrodynamical and mathematical problems associated with the motion of water waves on a sloping solid boundary make simulation of the runup process very difficult. The water motion near the runup front is strongly nonlinear in comparison to the motions away from the front. Waves near the front can break, and the flow can become turbulent. The wave behavior at the shoreline depends on such characteristics as the relationships between wavelength and water depth and between the length of the wave and its height.

This animation by Prof. Miho Aoki illustrates how a coastal town gets inundated by a tsunami wave. When a wave is generated by a subduction zone earthquake, the offshore part of the ocean bottom uplifts, and the land along the coast subsides. This type of bottom displacement propagates the wave toward the coast line with a leading trough, and this is the reason why the water sometimes recedes before the arrival of a tsunami wave, as it is illustrated by the animation.

Using the numerical model, we propagated the 1964 tsunami wave from the source to different coastal locations through the set of embedded grids. The map below shows the Kodiak Naval Station, where the blue line indicates how far inland the water has traveled in 1964.

This animation shows the waves inundating the Kodiak Naval Station, with white color representing the highest wave amplitudes. The time interval is 1 to 4 hours after the earthquake.