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Micromorphological Analysis of Coastal Sediments from Willapa Bay, Washington, USA: A Technique for Analysing Inferred Tsunami Deposits

Kilfeather, A.A.; Blackford, J.J.; Jaap, J.M. van der Meer

Authors

A.A. Kilfeather

J.J. Blackford

J.M. van der Meer Jaap



Abstract

Tsunami deposits are provisionally distinguished in the field on the basis of anomalous sand horizons, fining-up and fining-landward, coupled with organic-rich, fragmented `backwash' sediments. In this paper, micromorphological features of a sediment sequence previously interpreted as being of tsunami origin are described. These characteristics are shown to be consistent with the macro-scale features used elsewhere, but show additional details not seen in standard stratigraphies, including possible evidence for individual waves, possibly wave-magnitude progression, organic fragment alignment and intraclast microstructures. Although replication and more complete studies are needed, this analysis confirms the identification of a tsunami in Willapa Bay in ca.1700 AD, while demonstrating a widely applicable technique for confirming or refuting possible tsunami deposits.

Citation

Kilfeather, A., Blackford, J., & Jaap, J. V. D. M. (2007). Micromorphological Analysis of Coastal Sediments from Willapa Bay, Washington, USA: A Technique for Analysing Inferred Tsunami Deposits. Pure and Applied Geophysics, 164(2-3), 509-525. https://doi.org/10.1007/s00024-006-0173-4

Journal Article Type Article
Publication Date Mar 1, 2007
Deposit Date Sep 16, 2009
Journal Pure and Applied Geophysics
Print ISSN 0033-4553
Publisher Springer
Peer Reviewed Peer Reviewed
Volume 164
Issue 2-3
Pages 509-525
DOI https://doi.org/10.1007/s00024-006-0173-4
Keywords Tsunami, Micromorphology, Cascadia subduction zone, Willapa Bay, Washington, Thin sections.
Publisher URL http://www.springerlink.com/content/g7151568l72044n2/fulltext.pdf