Yamanaka, Y., Matsuba, Y., Shimozono, T., & Tajima, Y. (2025). Tsunami penetration along a river: insights from the tsunami following the 2024 Noto Peninsula Earthquake, Japan. Coastal Engineering Journal, 1–21.
2024年1月1日に発生した令和6年能登半島地震によって、新潟県関川では上流へ遡上する津波が確認されました。この研究では、監視カメラによる映像を用いた水位・流速の解析を行いました。その結果、流速にして10 m/sを超える速度で遡上していたことが分かりました。さらにそれら観測結果をもとに数値モデルの精度検証を行い、河川の地形や海岸構造物が津波に与える影響について分析を行っています。
A large tsunami, generated by a magnitude 7.6 earthquake on January 1 2024, traveled across the Sea of Japan and caused extensive damage along the surrounding coastlines. This study examined the tsunami characteristics in the Naoetsu coastal region of Joetsu City, Niigata Prefecture, an area characterized by featuring rivers, ports, and coastal infrastructure, and for which extensive observational data are available. The analysis integrated field surveys, image-based observations, and numerical simulations. The numerical results successfully reproduced tsunami behavior as captured by video footage and recorded by wave and tide gauges. The analysis indicated that the maximum water surface elevation exceeded 7 m above mean sea level in the coastal zone, and that flow velocities in the Seki River reached up to 10 m/s. Additional case studies were conducted to assess the influence of riverbed variations and coastal structures on tsunami dynamics. The results suggested that riverbed elevation changes during the tsunami substantially affected the flow rate and water surface elevation along the river. Furthermore, the breakwaters of Naoetsu Port were found to play dual roles – attenuating tsunami forces in adjacent coastal areas while intensifying tsunami intrusion along the channel of Seki River.