4:15 PM - 4:30 PM
[HDS10-10] Uncovering tsunami wave characteristics in Iida Bay, Ishikawa Prefecture, due to the influence of bathymetry
Keywords:Tsunami, The 2024 Noto Peninsula earthquake, Iida Bay, Tsunami amplification mechanism, Trapped edge wave
The Iida Bay, located on the northeast coast of the Noto Peninsula, Ishikawa Prefecture, Japan, was hit by a remarkably tsunami heights following the M7.6 earthquake on January 1, 2024. The simulated tsunami snapshots show significant tsunami amplification around Iida Bay. This study aims to study the tsunami wave characteristics in Iida Bay using numerical tsunami simulations based on the following three perspectives.
1. Tsunami characteristics in Iida Bay
Numerical simulation shows the maximum tsunami heights of 3.5m in Iida Bay, accompanied with the arrival of second wave. The snapshots of the tsunami propagation show that the reflection waves from the tip of the Noto Peninsula are entrapped and propagated along the coast as edge wave.
2. The influence of bathymetry
Numerical simulations ae carried out to investigate the Iida spurs’ effect on tsunami propagation. The simulation is applied to two different bathymetry settings based on bathymetry data (i.e., 45m) of Masuda et al., 2024. The first one is the original bathymetry data of Masuda et al., 2024, while for the second one, the sea depth greater than 200 m is replaced with uniform 200 m. Simulation on the original bathymetry data show that the reflected wave from the coastline is entrapped and propagates alongshore, resulting remarkable tsunami amplification. This phenomenon can no longer be seen in the simulation performed on the modified bathymetry data. This suggests that the bathymetry influence tsunami characteristics of Iida Bay, such as local amplification.
3. The effect of fault plane orientations
Aside from the bathymetry influence, the fault plane orientations can affect the tsunami characteristics. Numerical simulation is performed based on the validated source model of Masuda et al., 2024, but with fault strike varied by ±10. The results showed that the maximum tsunami height decreases as the fault planes locate perpendicular to the coast. This is because the fault plane is located at the shallow water depth, and therefore, the potential energy is smaller. Similar mechanisms are observed from the numerical simulations conducted based on the active faults (Earthquake Research Committee, August 2024) around the Noto Peninsula. Our study shows that the tsunami amplification mechanisms in Iida Bay can be affected by the bathymetry configuration and the strike angle of the fault planes. Our findings have implications for improvement of tsunami early warning and risk assessment to future tsunamis in Japan Sea.
1. Tsunami characteristics in Iida Bay
Numerical simulation shows the maximum tsunami heights of 3.5m in Iida Bay, accompanied with the arrival of second wave. The snapshots of the tsunami propagation show that the reflection waves from the tip of the Noto Peninsula are entrapped and propagated along the coast as edge wave.
2. The influence of bathymetry
Numerical simulations ae carried out to investigate the Iida spurs’ effect on tsunami propagation. The simulation is applied to two different bathymetry settings based on bathymetry data (i.e., 45m) of Masuda et al., 2024. The first one is the original bathymetry data of Masuda et al., 2024, while for the second one, the sea depth greater than 200 m is replaced with uniform 200 m. Simulation on the original bathymetry data show that the reflected wave from the coastline is entrapped and propagates alongshore, resulting remarkable tsunami amplification. This phenomenon can no longer be seen in the simulation performed on the modified bathymetry data. This suggests that the bathymetry influence tsunami characteristics of Iida Bay, such as local amplification.
3. The effect of fault plane orientations
Aside from the bathymetry influence, the fault plane orientations can affect the tsunami characteristics. Numerical simulation is performed based on the validated source model of Masuda et al., 2024, but with fault strike varied by ±10. The results showed that the maximum tsunami height decreases as the fault planes locate perpendicular to the coast. This is because the fault plane is located at the shallow water depth, and therefore, the potential energy is smaller. Similar mechanisms are observed from the numerical simulations conducted based on the active faults (Earthquake Research Committee, August 2024) around the Noto Peninsula. Our study shows that the tsunami amplification mechanisms in Iida Bay can be affected by the bathymetry configuration and the strike angle of the fault planes. Our findings have implications for improvement of tsunami early warning and risk assessment to future tsunamis in Japan Sea.