Zheng, Y., Matsuba, Y. & Tajima, Y. (2026) Numerical experiments on the potential hazard of the tsunami merging with winter storm waves after the Noto Peninsula earthquake. Coastal Engineering Journal, 1–16.
令和6年能登半島地震の津波来襲時にLiDARによって得られた波の遡上高をもとに、津波と風波の重合現象の数値モデルによる再現を行いました。結果、既存モデルのXBeach-NHを用いることで、風波と津波の重合による遡上高の増加を正確に再現することができました。また、十分に精度検証されたモデルを用いることで、他の日付・時刻に津波が来襲していた場合について、数値実験を行いました。結果、津波と風波が重合することで津波だけ考慮する場合より遡上高が大きくなる一方、それぞれの線形な重ね合わせと比べると、風波が海浜地形の影響を受けるため遡上高が小さくなることが分かりました。
The Noto Peninsula Earthquake that occurred on January 1, 2024, triggered tsunamis in the Sea of Japan, creating coastal hazards along the coastline of the Hokuriku region of Japan. On the day of the earthquake, the region was affected by winter storm waves, though the waves were not severe during the tsunami arrival. In this study, numerical experiments were conducted to assess the potential hazards of this tsunami occurring under storm wave conditions using the XBeach non-hydrostatic model. The model was validated against field data measured 150 km southwest of the epicenter. Model results indicate that the combination of the tsunami with wind waves increases the wave runup heights under rough wave conditions, while the contribution of the tsunami to shoreline excursions is strongly affected by the beach topography. The tsunami water level changes shift the swash zone along the concave beach profile, indirectly enhancing or reducing wind wave runup depending on the varying slope in the swash zone. Moreover, the presence of a high beach berm effectively constrains the wave runup, protecting the coastal zone from possible inundation. These findings highlight the importance of interactions among tsunamis, wind waves, and coastal morphology in hazard assessments and disaster mitigation planning.