Information on palaeo-tsunami magnitude is scientifically and socially essential to mitigate tsunami risk. However, estimating palaeo-tsunami parameters (e.g., inundation distance) from sediments is not simple because tsunami deposits reflect complex transport processes. Here, we show a new approach to estimate tsunami inundation distance based on the mixture ratio of gravels from several sources in tsunami deposits. We measured the roundness of source gravels in modern beach and fluvial deposits in a coastal valley in Japan through image analysis and then calculated the mixture ratio of both sediment types in tsunami deposits. Normalising the mixture ratios by inundation distances revealed an abrupt change in the mixture ratio at a constant percentile, regardless of tsunami magnitude. This relation allowed estimation of the inundation distance of palaeo-tsunamis during the last 4000 years.
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http://dx.doi.org/10.1038/s41598-019-46584-z | DOI Listing |
Sci Rep
January 2025
Faculty of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8572, Japan.
We examined the potential of environmental DNA (eDNA) for identifying tsunami deposits in the geological record using lake-bottom sediments in the Tohoku region, Japan. The presence of eDNA from marine organisms in a lacustrine event deposit provides very strong evidence that the deposit was formed by an influx of water from the ocean. The diverse DNA assemblage in the deposit formed by the 2011 Tohoku-oki tsunami included DNA of marine origin indicating that eDNA has potential as an identifying proxy for tsunami deposits.
View Article and Find Full Text PDFMar Pollut Bull
October 2024
TelePIX Co. Ltd., 2 Gukjegeumyung-ro 8-gil, Yeongdeungpo-gu, Seoul 07330, Republic of Korea.
Using satellite remote sensing, we show the distribution, dominant type, and amounts of marine debris off the northeast coast of Japan after the Great East Japan Earthquake on 11 March 2011 and subsequent tsunami. Extensive marine debris was found on March 12, with the maximal amount found on March 13. The debris was found to be mainly wood (possibly lumber wood), with an estimated 1.
View Article and Find Full Text PDFPLoS One
April 2024
Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Chiba, Japan.
Nat Commun
April 2024
Norwegian Geotechnical Institute (NGI), P.O. Box. 3930 Ullevål Stadion, N-0806, Oslo, Norway.
The 8200-year BP cooling event is reconstructed in part from sediments in the Norwegian and North Seas. Here we show that these sediments have been reworked by the Storegga tsunami - dated to the coldest decades of the 8.2 ka event.
View Article and Find Full Text PDFSci Rep
February 2024
Faculté des sciences de Sfax, universite de Sfax, Sfax, Tunisia.
New field investigations along the East Tunisian coastline reveal sedimentary deposits and damaged localities that may account for a catastrophic event during the late Holocene. North of Sfax city, ~ 3.4 m high cliff coastal marine and alluvial terraces show 20 to 50-cm-thick chaotic layer with sandy coarse gravels mixed with reworked pebbles, broken shells of gastropods and molluscs, organic matter and Roman pottery.
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