Pelagic smectite as an important factor in tsunamigenic slip along the Japan Trench

Research Article| February 01, 2015 Pelagic smectite as an important factor in tsunamigenic slip along the Japan Trench Jun Kameda; Jun Kameda * 1Department of Natural History Sciences, Graduate School of Science, Hokkaido University, N10 W8, Sapporo 060-0810, Japan *E-mail: kameda@mail.sci.hokudai.ac.jp Search for other works by this author on: GSW Google Scholar Mayuko Shimizu; Mayuko Shimizu 2Department of Earth and Planetary Science, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan †Current address: Neotectonics Research Group, Japan Atomic Energy Agency, Toki, Gifu 509-5102, Japan. Search for other works by this author on: GSW Google Scholar Kohtaro Ujiie; Kohtaro Ujiie 3Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-0006, Japan Search for other works by this author on: GSW Google Scholar Takehiro Hirose; Takehiro Hirose 4Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology, 200 Monobe Otsu, Nankoku City, Kochi 783-8502, Japan Search for other works by this author on: GSW Google Scholar Matt Ikari; Matt Ikari 5Center for Marine Environmental Science (MARUM), University of Bremen, Leobener Strasse, D-28359 Bremen, Germany Search for other works by this author on: GSW Google Scholar James Mori; James Mori 6Earthquake Hazards Division Disaster Prevention Research Institute, Kyoto University, Gokasho, Uji Kyoto 611-0011, Japan Search for other works by this author on: GSW Google Scholar Kiyokazu Oohashi; Kiyokazu Oohashi 7Department of Earth Sciences, Graduate School of Science, Chiba University, Chiba 263-8522, Japan §Current address: Department of Earth Science, Graduate School of Science and Engineering, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8512, Japan. Search for other works by this author on: GSW Google Scholar Gaku Kimura Gaku Kimura 2Department of Earth and Planetary Science, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan Search for other works by this author on: GSW Google Scholar Author and Article Information Jun Kameda * 1Department of Natural History Sciences, Graduate School of Science, Hokkaido University, N10 W8, Sapporo 060-0810, Japan Mayuko Shimizu †Current address: Neotectonics Research Group, Japan Atomic Energy Agency, Toki, Gifu 509-5102, Japan. 2Department of Earth and Planetary Science, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan Kohtaro Ujiie 3Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba 305-0006, Japan Takehiro Hirose 4Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology, 200 Monobe Otsu, Nankoku City, Kochi 783-8502, Japan Matt Ikari 5Center for Marine Environmental Science (MARUM), University of Bremen, Leobener Strasse, D-28359 Bremen, Germany James Mori 6Earthquake Hazards Division Disaster Prevention Research Institute, Kyoto University, Gokasho, Uji Kyoto 611-0011, Japan Kiyokazu Oohashi §Current address: Department of Earth Science, Graduate School of Science and Engineering, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8512, Japan. 7Department of Earth Sciences, Graduate School of Science, Chiba University, Chiba 263-8522, Japan Gaku Kimura 2Department of Earth and Planetary Science, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan *E-mail: kameda@mail.sci.hokudai.ac.jp Publisher: Geological Society of America Received: 03 Jun 2014 Revision Received: 01 Dec 2014 Accepted: 02 Dec 2014 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 © 2015 Geological Society of America Geology (2015) 43 (2): 155–158. https://doi.org/10.1130/G35948.1 Article history Received: 03 Jun 2014 Revision Received: 01 Dec 2014 Accepted: 02 Dec 2014 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Jun Kameda, Mayuko Shimizu, Kohtaro Ujiie, Takehiro Hirose, Matt Ikari, James Mori, Kiyokazu Oohashi, Gaku Kimura; Pelagic smectite as an important factor in tsunamigenic slip along the Japan Trench. Geology 2015;; 43 (2): 155–158. doi: https://doi.org/10.1130/G35948.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract The very large slip on the shallow portion of the subduction interface during the 2011 Tohoku-oki earthquake (Mw 9.0) caused a huge tsunami along the northeast coast of Honshu, Japan. In order to elucidate the mechanics of such tsunamigenic slip, the Integrated Ocean Drilling Program Expedition 343 (Japan Trench Fast Drilling Project, JFAST), was carried out one year after the earthquake and succeeded in recovering rocks constituting the active plate boundary fault. Our mineralogical analyses using X-ray diffraction reveal that the shallow portion of the fault zone that caused the earthquake is significantly enriched in smectite compared to the surrounding sediments, which may be intimately linked to the tsunamigenic shallow faulting. For comparison, we also analyzed mineralogical features of incoming sediments just prior to subduction, recovered on the outer rise of the Japan Trench (Site 436, Deep Sea Drilling Project Leg 56), and found a characteristic smectite-rich horizon in the uppermost ∼5 m of the pelagic clay layer. This horizon should be mechanically weak and will become the future plate boundary fault, as observed in the JFAST cores. The smectite-rich deposits are broadly distributed in the northwestern Pacific Ocean, and may therefore potentially enhance conditions for large shallow slip during earthquakes that occur over a broad area of the Japan Trench plate boundary, which would result in large tsunamis for this region. 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