Processes of submarine topographical change and　sediment supply of Suzu, Noto Peninsula, Japan

Abstract

We collected high resolution bathymetric data and sediment samples at off the coast of Suzu, the Northeast of Noto peninsula, central Japan before the 2024 Noto Hanto Earthquake. Using multibeam-echo-sounding equipment, we updated the bathymetric imagery of the area with high resolution and compared slope failures with those in previous studies. The obtained imagery, however, reveals that there is no evidence of large-scale collapses as suggested by the previous studies, and many small-scale failures are found at the south slope. Previous studies in this region indicated that the wet density of sediments ranges 1.3-1.5 g/cm³ and it tends to decrease from the shelf to the ocean basin. Our sampling data show 1.47 g/cm³ and the decreasing curve is consistent with previous studies. In order to discuss the sediment transportation processes, we analyzed constituent minerals and foraminifera. Based on these data, sediments are continuously transported from inland through the upper part of the continental shelf slope to the oceanic basin by persistent and weak bottom currents rather than by sporadic and strong currents caused by large earthquakes and typhoons which can generate a turbidite layer.