Chemical analysis of tsunami deposits; High spatial resolution measurement using scanning X-ray analytical microscope

Watanabe, Takahiro   ; Nara, Fumiko*; Ueki, Tadamasa*; Tsuchiya, Noriyoshi*

The identification of past tsunami deposits is important task for the risk assessment of major subduction zone earthquakes. Geological investigation now requires more reliable and precise identification of tsunami deposits and reconstructions of inundation limits than before. A tsunami deposit is preliminarily identified as an exotic layer within deposits that settled out in calm environments. The exotic deposit is then characterized using multiple criteria such as the lateral extent of the layer, changes in grain size, sedimentological features, and micropaleontology. Among the criteria, geochemical analysis is used to estimate the source of the sediments. Here, we tested inorganic geochemical analyses of the paleo tsunami deposits using XGT.