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Riou, Brieuc; Chaumillon, Eric; Chagu, Catherine; Sabatier, Pierre; Schneider, Jean-luc; Walsh, John-patrick; Zawadzki, Atun; Fierro, Daniela. |
Following recent tsunamis, most studies have focused on the onshore deposits, while the offshore backwash deposits, crucial for a better understanding of the hydrodynamic processes during such events and offering an opportunity for sedimentary archives of past tsunamis, have mostly been omitted. Here, we present a unique sedimentary record of the backwash from two historical tsunamis sampled in a sheltered bay in American Samoa, namely the 2009 South Pacific Tsunami and the 1960 Great Chilean Earthquake Tsunami. Although not always concomitant with a marked grain size change, backwash deposits are identified by terrestrial geochemical and mineralogical signatures, associated with basal soft sediment micro-deformations. These micro-deformations, including... |
Tipo: Text |
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Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00659/77079/78407.pdf |
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Riou, Brieuc; Chaumillon, Eric; Schneider, Jean‐luc; Corrège, Thierry; Chagué, Catherine. |
Extensive bathymetric and two‐dimensional seismic surveys have been carried out and cores collected in Pago Pago Bay (Tutuila, American Samoa) in order to describe and gain a better understanding of the sediment fill of the bay, which was affected by the 2009 South Pacific Tsunami. Eight sedimentary units were identified over the volcanic bedrock. The basal transgressive unit displays retrograding onlaps towards the shore, whereas the overlying seven aggradational layers alternate between four draping units and three pinching out seaward units. ‘Core to seismic’ correlation reveals that draping units are composed of homogeneous silts, while pinching out units are dominated by very coarse coral fragments showing fresh cuts, mixed with Halimeda plates. The... |
Tipo: Text |
Palavras-chave: Core to seismic correlation; Holocene; Sediment bay-fill; Shallow marine tsunami deposits; Tectonic activity cycles; Tsunami. |
Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00501/61231/76154.pdf |
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