HR: 1340h
AN: S53A-1043    [Abstracts]
TI: Source of Run-up Tsunami Deposits Based on Foraminiferal Tests Transportation and their Hydrodynamic Verification
AU: * Uchida, J
EM: utty@es.sci.kumamoto-u.ac.jp
AF: Kumamoto University, 39-1,Kurokami 2-chome, Kumamoto, 860-8555, Japan
AU: Fujiwara, O
EM: o.fujiwara@aist.go.jp
AF: Active Fault Research Center, National Institute of Advanced Industrial Science and Technology Site 7,1-1-1, Higashi, Tsukuba, 305-8567, Japan
AU: Abe, K
EM: abekohei@arsia.geo.tsukuba.ac.jp
AF: Tsukuba University, 1-1-1, Tennodai, Tsukuba, 305-8577, Japan
AU: Hasegawa, S
EM: shiro@sci.kumamoto-u.ac.jp
AF: Kumamoto University, 39-1,Kurokami 2-chome, Kumamoto, 860-8555, Japan
AB: Foraminiferal tests are often yielded in tsunami deposits and provide important information on the source of sediment supply. Water depth of sediment source areas and transport distance from the source areas estimated from the foraminiferal tests may be useful criteria to identify the tsunami deposits. Tractive force by tsunami waves is in inverse proportion to the water depth at depositional sites. Horizontal distance of sediment transport by tsunami waves is proportion to the period and amplitude of the waves. Then, threshold amplitude and period of tsunami waves to explain the sediment transport depend mainly on the weight of sediment grains and water depth of depositional sites. Some washover and near-shore deposits yield the foraminiferal tests transported long distance from deep marine bottom. These deposits are likely to result from tsunamis with large wave period and amplitude. Foraminiferal tests reported from some tsunami deposits indicate that they were originated from 100m or deeper sea floor and transported a long distance, up to several kilo meters, to the coasts. However, theoretical amplitude of tsunami waves to explain the transport of the foraminiferal tests is unusually large. Change in the action of the tsunami water mass affected by local topography, such as submarine canyons, is convincing cause of the contradictions in sediment transportation estimated from foraminiferal tests and from theories of tsunami propagation.
DE: 3022 Marine sediments: processes and transport
DE: 4564 Tsunamis and storm surges
DE: 4944 Micropaleontology (0459, 3030)
DE: 4950 Paleoecology
DE: 7221 Paleoseismology (8036)
SC: Seismology [S]
MN: 2007 Fall Meeting