Organic geochemical investigation of far‐field tsunami deposits of the Kahana Valley, O'ahu, Hawai'i

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Far‐field tsunami deposits observed in the Kahana Valley, O'ahu, Hawai'i (USA), were investigated for their organic‐geochemical content. During short high‐energy events, (tsunamis and storms) organic and chemical components are transported with sediment from marine to terrestrial areas. This study investigates the use of anthropogenic based organic geochemical compounds (such as polycyclic aromatic hydrocarbons, pesticides and organochlorides) as a means to identify tsunami deposits. Samples were processed by solid‐liquid extraction and analyzed using gas chromatography–mass spectrometry. A total of 21 anthropogenic marker compounds were identified, of which 11 compounds were selected for detailed analysis. Although the tsunami deposits pre‐date industrial activity in Hawaii by several hundred years, distinct changes were found in the concentrations of anthropogenic marker compounds between sandy tsunami deposits and the surrounding mud/peat layers, which may help in identifying tsunami deposits within cores. As expected, low overall concentrations of anthropogenic markers and pollutants were observed due to the lack of industrial input‐sources and little anthropogenic environmental impact at the study site. This geochemical characterization of tsunami deposits shows that anthropogenic markers have significant potential as another high‐resolution, multi‐proxy method for identifying tsunamis in the sedimentary record.

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Publication type Article
Publication Subtype Journal Article
Title Organic geochemical investigation of far‐field tsunami deposits of the Kahana Valley, O'ahu, Hawai'i
Series title Sedimentology
DOI 10.1111/sed.12583
Volume 67
Issue 3
Year Published 2020
Language English
Publisher Wiley
Contributing office(s) Geologic Hazards Science Center, Pacific Coastal and Marine Science Center
Description 19 p.
First page 1230
Last page 1248
Country United States
State Hawai'i
Other Geospatial Kahana Valley, O'ahu
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