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[MIS01-08] Relationship between typhoon-induced hazards in East Asia, pressure and SST pattern in Pacific Ocean during the Middle to Late Holocene
Keywords:Sediment, Lake Suigetsu, Typhoon, El Nino
Because flood events recorded in sediment and speleothem can be traced back to geologic past beyond the instrumental observation, analyzing these records can contribute to resolving the spatio-temporal pattern of typhoon-induced hazards and relationship between huge typhoons and background climatological setting in long term.
In this study, we quantitatively reconstructed flood records in the Japan Sea side of central Japan based on the occurrence and thickness of event layers in Lake Suigetsu. It has been proved that event layers of the Lake Suigetsu sediments were formed by floods induced by typhoons and their thicknesses represent the total precipitation caused by the typhoon. As the age model of the sediment in Lake Suigetsu during the Holocene is firmly established based on terrestrial 14C dating, this record could be correlated to other records in high resolution.
Flood records in Lake Suigetsu revealed that exceptionally huge flood events repeatedly occurred with murti-centennial periodicity and shows a similar millennial-scale pattern with flood record in speleothem of South China. In the long term, the two flood records show high frequency and intensity of flood events that are associated with the eastward spreading of high SST area in the equatorial area of Pacific Ocean. On the other hand, in centennial time scale, regional difference in paleo-flood records in South China and SW Japan is observed suggesting that pressure pattern or other conditions would also control the long-term variability of tracks of typhoons, in turn, regionality of typhoon-induced flood events.