Tsunami-Tide Interaction in the Seto Inland Sea, Japan

Abstract

Tsunami-tide interactions in the Seto Inland Sea (SIS) were investigated by taking into account the effects of tidal currents on the tsunami propagation in terms of the arrival time and the run-up heights along the coast of SIS. The initial tsunami wave profile was introduced by the possible Tokai-Tonankai-Nankai Earthquake of the magnitude Mw9.0, which is equivalent to that of 2011 Tohoku Earthquake. Numerical experiments with four different tidal phases, flood, ebb, high, and low, reveal that the water depth changes due to tides affect the tsunami propagation in terms of heights and arrival time. During high tides, the tsunami propagates faster and reaches higher than during the low tides. In addition, during the flood tides with rising water level, tsunami propagates faster than during the ebb tides. Further investigation also shows that the tsunami-tide interaction changes the tsunami signal such that the tsunami-only spectra shifts the spectral peaks after considering the tsunami-tide interactions. Local oscillation modes characterized by local bathymetry and topography shift to higher frequency modes due to the non-linear tsunami-tide interaction. To reduce the uncertainties involved in tsunami predictions and coastal defenses and management, it is strongly recommended to simulate tsunamis together with tides in shallow water environments.

Tsunami Inundation Modelling in a Built-In Coastal Environment with Adaptive Mesh Refinement: The Onagawa Benchmark Test

“…Hence, fluid motion is simulated on a 2D quadtree mesh via the vertical integration of the horizontal components of water velocity [28,29]. Many studies have proven the efficacy of this approach when paired with the Gerris flow solver in determining tsunami propagation nearshore where long wave approximation with negligible water depth is valid [28,29,32,34,35].…”

Impacts of tides on tsunami propagation due to potential Nankai Trough earthquakes in the Seto Inland Sea, Japan

“…The potential Takai-Tonankai-Nankai-linked earthquake and tsunami source region along the Nankai Trough, which was revised and issued by the Central Disaster Prevention Council, Japan (modified from Figure V Journal of Geophysical Research: Oceans 10.1002/2015JC010995 Japan, the tide and tidal currents are high and very strong and are dominant physical processes in the SIS's coastal environment. Therefore, taking the impacts of tides and tidal currents on extreme tsunami propagation in the SIS into account is critical for coastal protection and disaster prevention [Lee and Kaneko, 2015;Lee et al, 2010;Shimoyama and Lee, 2014].…”

“…Therefore, taking the impacts of tides and tidal currents on extreme tsunami propagation in the SIS into account is critical for coastal protection and disaster prevention [Lee and Kaneko, 2015;Lee et al, 2010;Shimoyama and Lee, 2014].…”