11:15 AM - 11:30 AM
[MIS20-07] Holocene coastal barrier dune development and its influence on coastal inundation along Kochi coast, facing Nankai Trough
Keywords:tsunami, coastal barrier dune, ground-penetrating radar (GPR), optically stimulated luminescence (OSL) dating, Kochi Prefecture, Nankai Trough
Coastal lowlands are appropriate for the studies on tsunami deposits. However, they have undergone significant environmental changes such as shoreline migration and coastal dune development throughout the Holocene. Therefore evaluating the changes in coastal environment is important for understanding the coastal flooding history.
We examined ground-penetrating radar (GPR) profiles, optically stimulated luminescence (OSL) dating, and radiocarbon dating with a coastal barrier dune in Nankoku, Kochi Prefecture facing Nankai Trough. Based on these analyses, the Holocene coastal barrier dune development is probably divided into two phases. First, between 6000-2600 cal BP, the dune aggraded upward to about 10 m high, and the main body of the dune was formed. Second, after 2600 cal BP, the dune accreted laterally, mainly seaward, and its width was enlarged. A geological study in a lowland behind the dune reported four event deposits originated from coastal inundations between 6400-2400 cal BP, in contrast, no event deposit between 2400-900 cal BP (Tanigawa et al., 2018). The history of coastal barrier dune development and coastal inundation suggests that no inundation evidence after 2400 cal BP is likely to be controlled by the formation of the dune main body until 2600 cal BP.
This study was supported by funding from the 'Research Project for Disaster Prevention on the Great Earthquakes along the Nankai Trough' by the Ministry of Education, Culture, Sports and Technology of Japan (MEXT).
We examined ground-penetrating radar (GPR) profiles, optically stimulated luminescence (OSL) dating, and radiocarbon dating with a coastal barrier dune in Nankoku, Kochi Prefecture facing Nankai Trough. Based on these analyses, the Holocene coastal barrier dune development is probably divided into two phases. First, between 6000-2600 cal BP, the dune aggraded upward to about 10 m high, and the main body of the dune was formed. Second, after 2600 cal BP, the dune accreted laterally, mainly seaward, and its width was enlarged. A geological study in a lowland behind the dune reported four event deposits originated from coastal inundations between 6400-2400 cal BP, in contrast, no event deposit between 2400-900 cal BP (Tanigawa et al., 2018). The history of coastal barrier dune development and coastal inundation suggests that no inundation evidence after 2400 cal BP is likely to be controlled by the formation of the dune main body until 2600 cal BP.
This study was supported by funding from the 'Research Project for Disaster Prevention on the Great Earthquakes along the Nankai Trough' by the Ministry of Education, Culture, Sports and Technology of Japan (MEXT).