Structural Analysis of Coseismic Normal Fault Zones of the 2011 Mw 6.6 Fukushima Earthquake, Northeast Japan

Abstract

Research Article| May 01, 2013 Structural Analysis of Coseismic Normal Fault Zones of the 2011 Mw 6.6 Fukushima Earthquake, Northeast Japan Aiming Lin; Aiming Lin Graduate School of Science and Technology, Shizuoka University, Shizuoka 422‐8529, Japan *Now at Department of Geophysics, Division of Earth and Planetary Sciences, Graduate School of Science, Kyoto University, Kyoto 606‐8502, Japan, [e-mail]. Search for other works by this author on: GSW Google Scholar Shinji Toda; Shinji Toda Disaster Prevention Research Institute, Kyoto University, Kyoto 611‐0011, Japan Search for other works by this author on: GSW Google Scholar Gang Rao; Gang Rao Graduate School of Science and Technology, Shizuoka University, Shizuoka 422‐8529, Japan Search for other works by this author on: GSW Google Scholar Satoru Tsuchihashi; Satoru Tsuchihashi Graduate School of Science and Technology, Shizuoka University, Shizuoka 422‐8529, Japan Search for other works by this author on: GSW Google Scholar Bing Yan Bing Yan Graduate School of Science and Technology, Shizuoka University, Shizuoka 422‐8529, Japan Search for other works by this author on: GSW Google Scholar Author and Article Information Aiming Lin *Now at Department of Geophysics, Division of Earth and Planetary Sciences, Graduate School of Science, Kyoto University, Kyoto 606‐8502, Japan, [e-mail]. Graduate School of Science and Technology, Shizuoka University, Shizuoka 422‐8529, Japan Shinji Toda Disaster Prevention Research Institute, Kyoto University, Kyoto 611‐0011, Japan Gang Rao Graduate School of Science and Technology, Shizuoka University, Shizuoka 422‐8529, Japan Satoru Tsuchihashi Graduate School of Science and Technology, Shizuoka University, Shizuoka 422‐8529, Japan Bing Yan Graduate School of Science and Technology, Shizuoka University, Shizuoka 422‐8529, Japan Publisher: Seismological Society of America First Online: 14 Jul 2017 Online ISSN: 1943-3573 Print ISSN: 0037-1106 Bulletin of the Seismological Society of America (2013) 103 (2B): 1603–1613. https://doi.org/10.1785/0120120111 Article history First Online: 14 Jul 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Aiming Lin, Shinji Toda, Gang Rao, Satoru Tsuchihashi, Bing Yan; Structural Analysis of Coseismic Normal Fault Zones of the 2011 Mw 6.6 Fukushima Earthquake, Northeast Japan. Bulletin of the Seismological Society of America 2013;; 103 (2B): 1603–1613. doi: https://doi.org/10.1785/0120120111 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 SocietyBulletin of the Seismological Society of America Search Advanced Search Abstract The 2011 Mw 6.6 Fukushima earthquake occurred in Iwaki City, ∼250 km southwest of the epicenter of the 2011 Mw 9.0 Tohoku (Japan) earthquake, and produced two subparallel ∼15–23‐km‐long surface rupture zones with distinct displacements along two pre‐existing normal faults: the Shionohira and Yunodake faults, which strike north‐northwest–south‐southeast and northwest–southeast (both dipping southwest), respectively. Field investigations and structural analysis of the coseismic shear zones developed within the Shionohira and Yunodake fault zones, reveal that (1) the coseismic shear zones consist of a fault core that includes a narrow fault gouge zone of <10 cm in width (generally 1–5 cm), a fault breccia zone of <50 cm in width, and a damage zone of 5–50 m in width that is composed of cataclastic rocks, fractures, and subsidiary faults; (2) the foliations characterized by S‐C fabrics developed in the shear zones indicate a dominantly normal fault‐slip sense, consistent with that observed along the coseismic surface ruptures; and (3) veinlet cataclastic rocks composed of unconsolidated fault gouges and fine‐grained materials occur as simple discrete veinlets and multiple, cross‐cutting, interconnected networks of veinlets. These newly documented structural characteristics for two coseismic fault/shear zones and associated cataclastic rocks indicate that the locations of coseismic slip zones associated with the 2011 Fukushima earthquake were controlled by pre‐existing fault/shear zones central to the Shionohira and Yunodake faults, which have repeatedly moved as seismogenic normal faults since the timing of formation of associated cataclastic rocks. Our results demonstrate that the structural analyses of coseismic shear/fault zones provide a powerful tool to study the nature and active faulting history of seismological faults. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.