Ostracodes reveal the sea-bed origin of tsunami deposits

In Rikuzentakata City, Ostracode assemblages in sediment deposited by the Tohoku‐Oki earthquake and tsunami of 11 March 2011 revealed that the sediment was derived from the seafloor from at least 9 m water depth, and was transported inland more than 1 km. The tsunami wave height at this location was higher than 10 m. Four hundred fifty seven modern ostracode assemblages were used in the modern analogue technique to estimate the depth source of the tsunami deposited assemblages. The application of this method to paleo‐tsunami deposits may provide insight into past tsunami wave height and potentially earthquake slip and magnitude.