Sedimentary Diversity of Tsunami Deposits in a River Channel Associated with the 2024 Noto Peninsula Earthquake, Central Japan

A comprehensive analysis of modern tsunami deposits offers a valuable opportunity to elucidate the characteristics of paleo-tsunami deposits. On 1 January 2024, a tsunami was generated by a magnitude 7.6 seismic event and subsequently struck the Noto Peninsula in central Japan. In order to create a facies model of the tsunami deposits in terrestrial and riverine environments, field surveys were conducted on both the onshore and sandbars within the river channel in the Nunoura area on the northeastern Noto Peninsula. Terrestrial tsunami deposits were observed up to several hundred meters inland, with a slight decrease in thickness of several centimeters with distance from the shoreline. In terrestrial settings, the presence of a substantial silty layer overlying a graded sandy layer is indicative of ponded stagnant water from the tsunami wave. In contrast, riverine tsunami deposits are thicker and more extensive than terrestrial sediments, containing both gravels and shell fragments. An erosional surface develops between deposits of run-up and backwash flows, but a mud drape is not observed.