[H-DS10] Tsunami and tsunami forecast

[HDS10-12] Impact of bathymetry, wave dispersion and epicenter location on the propagation of tsunamis in the Sea of Japan

Taiki Yamaguchi¹, *Uehara Katsuto¹ (1.Kyushu University)

Keywords:tsunamis, Sea of Japan, bathymetry, wave dispersion

Ray tracing of tsunamis generated in the Sea of Japan (SOJ) have been undertaken to investigate the nature of basin-wide tsunami propagation specific to this region. Tsunamis observed in the study area west of Japanese Islands generally show shorter wave period compared to those approaching to the east coast of Japan facing the main Pacific Ocean, whereas the water depth in the offshore Japan Sea is comparable to those in the main Pacific. The bathymetry of SOJ shows ragged feature at regions south of around 40N. To reflect these features, the ray tracing model used in this study adopted wave velocity without applying shallow-water approximation, and a special care was taken when preparing the model bathymetry. The experiment was made for three major tsunamis taken place at year 1983 (epicenter at around 40N), 1993 (north of 40N) and 2024 (south of 40N) originated from the eastern side of SOJ. Paths of the tsunami-wave propagation as well as their traveling times were compared with water levels observed at 24 tide-gauge stations situated around SOJ. Preliminary results obtained by analyzing wave paths approaching the Korean east coast, where high tsunami waves have observed at all three cases, indicate that it is necessary to consider the wave dispersion, i.e., not using shallow-water approximation, to reproduce realistic results for tsunamis propagating over SOJ, and the basin-wide propagation of tsunamis depends greatly on the meridional location of the epicenter. The outcome of this study could be applied to understand the nature of potential tsunamis generated in the South China Sea, where the bathymetric settings resemble to that of SOJ.