Abstract
In this study, a field survey was conducted on tsunami deposits that were formed on land and preserved within the strata of the island areas of Matsushima Bay, Miyagi Prefecture, as a result of the tsunami triggered by the 2011 off the Pacific coast of Tohoku Earthquake. As a result, the distribution patterns, preservation conditions, and relationships with topography of the tsunami deposits on the coast of Fukuura island in Matsushima Town were clarified. The factors determining the thickness and distribution patterns of the tsunami deposits are diverse, including the sources and grain sizes of the deposits on land, transport pathways, and the surrounding microtopography. However, the processes of formation and preservation of tsunami deposits on the coastal areas of the island－which are believed to have served as natural seawalls mitigating tsunami inundation in the inner part of Matsushima Bay－as well as methods for estimating tsunami magnitude in such contexts, have not yet been established. Based on the findings of this study, it is expected that examining the details of tsunami deposits on island coastal areas where inundation depths are unknown will contribute to the advancement of tsunami assessment methods based on tsunami deposits.
