Sedimentological Effect of Noto Tsunami in Ice Cover Conditions of the Sea of Japan Coast

The Noto tsunami inundation zone was surveyed in the field in Preobrazheniye Bay (Eastern Primorye) in late January and April 2024. Before the tsunami, the inner part of the bay began to freeze, forming fast and drift ice. Despite the low wave height and run-up (20–60 cm according to tacheometric survey results), an extensive silt–pelitic mud sheet was formed in the bay on unbroken fast ice and strongly consolidated ice, which covered the shore at the head of the bay (from 1.5 to 26 m). The total length of the silt sheet was 325 m. The tsunami penetrated along the frozen stream up to 680 m from the mouth, and the mud sheet and patches were encountered up to 250 m. Features of wave propagation were recorded by the position of grass blades, Zostera rollers and algal scraps. The grain size distribution of mud and biofossils (diatoms and benthic foraminifera) were studied. Changes in grain size and ecological groups of biofossils along the profiles were analyzed. Epiphytes predominated among the diatoms. Benthic foraminifera are mainly represented by agglutinating forms. The source of the material was the littoral and sublittoral, where water saturated with ice floes actively eroded bottom sediments. The implications of the results for paleotsunami searches are discussed.