2000 Volume 39 Issue 5 Pages 451-460
We found a thin sand layer above the peat intercalating two volcanic ash layers at Kiritappu marsh, eastern Hokkaido, Japan. We regard this sand layer as a tsunami deposit, because the spatial distribution and sedimentary facies are similar to those of typical tsunami deposits we have investigated. Our conclusion is also supported by fossil diatom assemblages in this area. The two ash layers are identified as Ta-a (1739 AD) and Ko-c2 (1694 AD). Based on these dates and the assumed growth rate of the peat layers, we estimate the date of the tsunami as to be between the 1810s and the 1850s. It is inferred, therefore, that the deposit originated from the 1843 AD earthquake tsunami, which caused 46 deaths in the Akkeshi area, eastern Hokkaido. Accoring to old doocuments, this tsunami was the only one that caused serious damage to Kiritappu area during the period from the 1810s to the 1850s.
