Distribution of tsunami deposits in the southern Kiritappu marsh, eastern Hokkaido, Japan

Abstract

Geological evidence of tsunamis recorded in the Kiritappu marsh, Hokkaido, Japan, provides a unique opportunity to study past giant earthquakes along the Kuril Trench. The landward limits of tsunami deposits in the northern marsh have been reported previously, whereas their limits remain uncertain in the southern marsh. Here we present the distribution of tsunami deposits at Ichibansawa in the southern Kiritappu marsh. Tephrochronology and ¹⁴C age data indicate that the sand bed in the seaward area of Ichibansawa is correlated with tsunami deposits of the 17^th century or the 13-14^th centuries. The sand bed in inland Ichibansawa is correlated with tsunami deposits of the 13-14^th centuries. The sheet-like distribution of the inland sand bed is also observed in a tributary of Ichibansawa. These results may constrain models of faults that generate large tsunamis along the Pacific coast of eastern Hokkaido.