[M-IS23] Developments and applications of non-destructive analyses in natural archives

[MIS23-P03] Tsunami inundation events postdating the 18th century along the Pacific coast of eastern Hokkaido, inferred from non-destructive analyses

*YUKI SAWAI¹, Yumi Shimada¹, Koichiro Tanigawa¹, Dan Matsumoto¹, Yuichi Namegaya¹, Kei Ioki¹ (1.National Institute of Advanced Industrial Science and Technology)

Keywords:XRF core scanner, CT images, Tsunami, Kuril trench

This study focuses on identifying event deposits formed after the 18th century, generated by tsunamis and storms, using non-destructive analyses along the Pacific coast of eastern Hokkaido.
Sediment samples postdating the 18th century were collected from the coasts of Nemuro, Hamanaka, and Taiki by excavating pits and using a handy geoslicer. We carried out non-destructive analyses (CT scanning and XRF analysis) on the samples in the laboratory. As a result, for example, high-density layers within the organic deposits/peat of the samples from Taiki were identified using X-ray computed tomography (CT) images. The XRF core scanner (ITRAX) detected clear peaks of Ca, Br, and Sr within these high-density layers. Based on chronology using Pb-210 and Cs-137, one of the high-density layers was found to correspond to the 1894 Nemuro earthquake.
[Acknowledgements] This study was performed under the cooperative research program of Marine Core Research Institute (MaCRI), Kochi University (22A002, 24A004, 24B004).