Geomorphological impact by the 1498 Meio earthquake on the Enshunada coastline, Central Japan

Osamu Fujiwara, Vanessa Heyvaert, Masatomu Umitsu, Einsuku Ono, Toshifumi Yata, Yoshiki Sato

Research output: Chapter in Book/Report/Conference proceedingMeeting abstract (Book)

Abstract

The palaeoenvironmental evolution of the Enshunada coastline, Hamamatsu area, located on the central island of Japan is investigated. More in particular the the impact of atsunami, generated by the 1498 Meio earthquake (M8.2-8.4) along the Nankai Through, on the geomorphological evolution of the Enshunada coastline is investigated.
Historical sources document the sudden decline at the end of the 15th century of an important harbour town Hashimoto, located along the river Hamana. This river connected the Pacific Ocean with a coastal embayment closed by a sand barrier (i.e. the present-day called Hamana lake) before the 15th Century.
During geological fieldwork (geoslicer and auger) the palaeochannel of the Hamana river was detected along the western side of the present-day Hamana coastal embayment. A detailed facies analysis of the undisturbed sediment cores was carried out.
On the basis of the sedimentological data, it is suggested that the Hamana river mouth became abruptly closed by the transport of huge volumes of sand by the Meio tsunami. This initiated the development of a marsh environment upstream along the channel. The same process, of sudden river mouth enclosure by tsunami-transported sediments was recently observed in the Northeast Japan during the great 2011 Sendai tsunami (Uda, T., 2011).
Moreover, our results show that due to the 1498 Meio tsunami, the Hamana back-barrier sheltered environment became again connected to the Pacific Ocean by breaching of its sand barrier. Both environmental changes (river mouth enclosure and barrier breaching) are synchronous with the sudden decline of the harbour town Hashimoto at the end of the 15th century. This suggests that the breaking-off of the water route connecting the harbour town Hashimoto and Pacific Ocean potentially led to the decline of the town.
Original languageEnglish
Title of host publicationAll at the sea conference, University of York, 8-9 September 2011
Publication statusPublished - 8 Sep 2011
EventUnknown -
Duration: 8 Sep 2011 → …

Publication series

NameAll at the sea conference, University of York, 8-9 September 2011

Conference

ConferenceUnknown
Period8/09/11 → …

Keywords

  • Tsunami

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