A new paper published in Natural Hazards today discusses post-depositional changes of tsunamites. At sites in Thailand covered by sediments of the 2004 Sumatra tsunami, Szczuciński (2011) has documented significant changes in the deposits over the last seven years. Not only were the tsunamites altered, eroded or re-deposited by animals and seasonal rain, but also vanished in certain cases.
This is important work since tsunamites are often used for paleoseismological analyses and seismic hazard assessment. It is now shown that – depending on the deposition environment – any study on paleotsunamis or sediment modelling needs to take into account those changes. Most likely the extend of tsunamites will be understimated due to erosion. Thin layers may not be found at all. The example of the 2004 tsunami has the great advantage that the same sites could have been probed repeatedly and directly compared.
Szczuciński, Witold (2011): The post-depositional changes of the onshore 2004
tsunami deposits on the Andaman Sea coast of Thailand. Nat Hazards