Figure 4.

PPG and the Global fallout recorded in the Beppu Bay sediments and coral radiocarbon and uranium measurements. Age model of the sediment taken from Beppu Bay is reconstructed using radioisotopes measurements in corals from Japan. A sharp Δ¹⁴C peak found in Ishigaki Coral at 1954.8 CE was attributed as the close in fallout signature¹³ which is consistent with uranium isotope ratio data obtained from Iki Is⁵⁹. Since Pu isotopes in Beppu Bay sediments clearly show a PPG value at 52.5 cm bsf in the core BMC19, it can be assigned to 1955.6 CE (Red dotted arrows). A linear sedimentation rate is applied to the section between this depth and 24.5 cm bsf (Ev.-1b; 1993.72 CE). The drop in total Pu was attributed to 1963 CE which is consistent with the uranium peak found in corals obtained from Iki (black dotted line), supporting the validity of the Beppu Bay sediment age model. The stratigraphy also verifies that the age of Ev.-1a, found at 46.0 cm bsf as derived from the age model as 1968 CE, is consistent with historical documents of the Hyuganada Earthquake Tsunami.