Field surveys of tsunami runup and damage following the January 2024 Mw 7.5 Noto (Japan Sea) tsunamigenic earthquake

Abstract

The 1st January 2024 Noto Peninsula Mw 7.5 tsunamigenic earthquake, with at least 241 deaths, was the most destructive event in Japan following the March 2011 Mw 9.0 catastrophic event. We conducted field surveys in the affected area 24 days after the event to document tsunami heights, runups, coseismic coastal uplift and damage to coastal structures. Here, we present the results of the surveys and analyze tsunami height distribution and associated damage. In our survey of 29 locations, tsunami runups and heights varied in the ranges of 4.4 – 6.2 m, and 1.0 – 4.4 m, respectively. Notably, Joetsu, the farthest location from the epicenter in our field survey, recorded the highest runup of 6.2 m, which is attributed to the directivity effect of tsunami waves. The maximum surveyed runup of 6.2 m closely aligns with the reported maximum fault slip of 4–6 m for this earthquake, confirming a long-established rule of thumb. Coastal crustal uplifts of up to 1.6 m have rendered many ports unsuitable for use. We identified three failure mechanisms affecting coastal structures: overturning caused by tsunami backwash, damage resulting from tsunami inundation currents and wave pressure, and impacts from floating objects and debris.