Field surveys of the 2024 Noto Peninsula earthquake tsunami in the areas distant from its source

Field surveys of tsunami heights caused by the January 1, 2024, Noto Peninsula earthquake (M 7.6, Japan Meteorological Agency) were conducted along approximately 700 km of coast from Yamagata Prefecture to Shimane Prefecture and on Sado Island, Japan. The region around the source area, which was severely damaged, was excluded. We measured tsunami heights of about 2–3 m at sites that were relatively close to the wave source area. The tsunami heights tended to be smaller or attenuated to an indistinguishable level at measurement points further away from the source area; however, a 1.4-m tsunami, which was higher than the tsunami heights in the surrounding areas, was found to have hit the port of Hyogo Prefecture, approximately 300 km from the wave source. To determine the overall magnitude of this tsunami, we estimated the tsunami magnitude m to be 1.5 from our measurement data and other published data. According to the relationship between the earthquake magnitude M and tsunami magnitude m of past earthquakes on the eastern margin of the Japan Sea, the m value of the 2024 tsunami was smaller than the value that would be expected from the earthquake magnitude.