Nearshore Propagation and Amplification of the Tsunami Following the 2024 Noto Peninsula Earthquake, Japan

On 1 January 2024, a massive earthquake struck the Noto Peninsula in Japan, and the resulting tsunami significantly damaged the nearby coasts. This study focuses on Iida Bay, located on the peninsula that suffered severe coastal damage. We observed a tsunami waveform in Iida Bay from video analysis owing to the lack of instrument data. This, combined with the waveform observed outside the bay, was used to correct the initial sea‐surface displacements produced by a prior source model. We successfully reproduced the observed waveforms with corrected displacements and investigated how the tsunami propagated and amplified in the bay. Alongshore wave propagation and superposition were identified as crucial factors in this tsunami event. Plain Language Summary On 1 January 2024, a large earthquake struck the Noto Peninsula in Japan, generating a tsunami that significantly impacted the nearby coasts. Post‐event surveys revealed severe damage to Iida Bay, located on the peninsula. To investigate tsunami propagation and amplification, we analyzed the images of the recorded video of the tsunami along with a numerical simulation. According to our results, the tsunami maximized during the subsequent waves rather than during the primary wave in the bay. Waves propagating along the shore developed after the primary wave of the tsunami, and some of these waves propagating from opposite sides of the bay overlapped at a specific location in the bay, where significant inundation was observed ∼20 min after the arrival of the primary wave. Key Points Generation, propagation, and amplification characteristics of a tsunami following the 2024 Noto Peninsula Earthquake were investigated Significant sea‐surface displacements were concentrated in the northeastern part of the source area Waves propagating in alongshore directions and their superposition greatly contributed to coastal damage in Iida Bay