[MIS12-P05] Multiproxies applied on sediment core for revealing the environmental changes and natural disaster events in Lake Kitaura, central Japan
Keywords:Lake Kitaura, sediment core, volcanic, disaster, Itrax
We found that the grain size of sediments was influenced by the volcanic eruption, typhoon, and tsunami events. Br/Ti and S/Ti ratio from Itrax core scanner gives us the information of environmental changes between marine and freshwater, and also indicate that the lagoon formed after about A.D. 1200. After the Mt. Fuji eruption in A.D. 1707, the river brought a lot of sediment accumulation at that time to cause the Br/Ti and S/Ti signals decreasing and forming a more closed brackish environment. We also can judge the duration of salt damage before the Hitachi River locks in A.D. 1975. The sediment cores may record the tsunami event of A.D. 1707, and frequent storm tides between A.D.1275-1340 closed to the time of Kamikaze typhoon in historical records.