Propagation of Tsunami Waves in a T-shaped Bay

Abstract

Based on the SWASH numerical hydrodynamic model, a study was made of the penetration of tsunami waves into a T-shaped bay, which has the characteristic dimensions and configuration of the Sevastopol Bay. To model the propagation of tsunami waves in the bay, a non-linear hydrodynamic non-hydrostatic SWASH model was used. To determine the boundary conditions at the liquid boundary of the computational domain, using the Black Sea tsunami model, we calculated sea level fluctuations at the entrance to the Sevastopol Bay during the propagation of tsunami waves from three hypothetical earthquake foci with magnitude M = 7. As a result of the penetration of a tsunami into a T-shaped bay of height waves increase by 2–2.5 times compared to the heights on the seashore of the bay. At the same time, at the top of the bay, the amplitude of sea level fluctuations can reach 0.8 m. The most intense fluctuations are observed in the first three hours of the tsunami action. Tsunamis from different foci cause seiche oscillations in the bay with periods of 49.1 min, 19.3 min, 9.2 min, 6.8 min. At the same time, the amplitude-phase characteristics of the tsunami have a significant effect on the redistribution of wave energy between the modes of seiche oscillations. Numerical experiments have shown that the presence or absence of protective breakwaters at the entrance to the bay does not lead to significant changes in the wave field and sea level heights during tsunami propagation inside the bay.