Sedimentary diversity of tsunami deposits in a river channel associated with the 2024 Noto Peninsula Earthquake, central Japan

Rina Okada, Koji Umeda, Keigo Motegi, Takanobu Kamataki, Tadashi Amano

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.

Geosceiences

MDPI AG

15

https://doi.org/10.3390/geosciences15040153