To identify paleo-tsunami history, we studied coastal lowland on Nikaho city, southern part of Akita Prefecture and Yuza town, northern part of Yamagata Prefecture, at the eastern margin of Japan Sea. These areas were known to have been affected by the 1804 Kisakata and the 1833 Off-Shonai earth-quake tsunamis, however these details are unknown. From boring cores in these study area, we found some coarse-grained sediments in organic mud and peat that were deposited in marsh and flood-plain. These coarse-grained sediments are event deposits. Some of these event deposits are interpreted as tsu-nami deposits. Depositional ages of these tsunami deposits were interpreted 12th–13th-century, 14th–15th-century and after 17th-century by calibrated ages.
Research papers (academic journals)