Quaternary International
Quaternary International
4 years ago

Subsidence along the central to southern Sanriku coast, northeast Japan, near the source region of the 2011 Tohoku-oki earthquake, estimated from the Holocene sedimentary succession along a ria coast

Along the Sanriku coast, northeast Japan, discrepancies in crustal movement have been reported between uplift on a scale of 105 years versus subsidence on a scale of 101–102 years. Well-dated Holocene incised-valley-fill sediments provide records of millennial-scale vertical crustal movement, which is key to understanding the tectonic history in this area. Previous studies of the age and distribution of early Holocene intertidal deposits in incised valleys reported that the southern Sanriku coast has subsided during the Holocene at an average rate of about 1 mm/yr. Here we studied three sediment cores, TGI1, TGI2, and TGI3, collected from the Tsugaruishi plain on the central Sanriku coast, and recognized a Holocene deltaic sediment succession in all three cores. In core TGI3, from the farthest inland site, the intertidal sediment facies, deposited from 7500 to 7000 cal BP, and the overlying 6-m-thick floodplain facies, deposited from 7000 to 5000 cal BP, are both below the present sea level. Because a sea-level highstand due to hydroisostatic uplift around Japan occurred in the mid-Holocene, we inferred that the Tsugaruishi plain subsided during the Holocene, and the estimated subsidence rate, 1.1–1.9 mm/yr at maximum, is consistent with the recently reported subsidence rate along the southern Sanriku coast. The results of this study confirm that the central to southern Sanriku coast is subsiding, in contrast to an interpretation based on the study of marine terraces that this part of the coast is uplifting. The empirical data presented here will be useful for constructing an earthquake cycle model related to plate subduction.

Publisher URL: www.sciencedirect.com/science

DOI: S1040618216313027

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

  • Download from Google Play
  • Download from App Store
  • Download from AppInChina

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.