Japan Geoscience Union Meeting 2016

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Poster

Symbol S (Solid Earth Sciences) » S-SS Seismology

[S-SS27] Fault Rheology and Earthquake Physics

Wed. May 25, 2016 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall HALL6)

Convener:*Takeshi Iinuma(National Research and Development Agency Japan Agency for Marine-Earth Science and Technology), Yuko Kase(Geological Survey of Japan, AIST), Ryosuke Ando(Graduate School of Science, University of Tokyo), Wataru Tanikawa(Japan Agency for Marine-Earth Science and Technology, Kochi Instutute for Core Sample Research), Hideki Mukoyoshi(Department of Geoscience Interdisciplinary Graduate School of Science and Engineering, Shimane University)

5:15 PM - 6:30 PM

[SSS27-P26] Structural and mineralogical characteristics of an ancient plate boundary fault in the Hidakagawa Formation, Kii Peninsula, Japan

*Takeaki Ogawa1, Naoki Kato1, Naoya Tonoike1, Satoru Asayama1, Shunya Kaneki1, Yuki Nakano1, Tetsuro Hirono1 (1.Department of Earth and Space Science, Graduate School of Science, Osaka University)

Keywords:plate boundary fault, accretionary prism, Nankai trough

To understand the slip behavior of mega earthquakes along plate boundary faults, geological studies of ancient seismogenic subduction faults in onland accretionary complexes such as Shimanto have been performed in providing important information about the characteristics of the fault-zone materials. Because the trench-parallel heterogeneity in the slip behavior of subduction earthquake is important to estimate the magnitude of the rapture area in the Nankai Trough, a more investigation at various regions in the Shimanto is required.
We here targeted the mélange unit of the Hidakagawa Formation, distributed around the Mio region, Kii Peninsula, and performed structural analysis of the fault rocks on the field and laboratory-based analyses such as XRD and SEM. We found a localized slip zone accompanying the evidence of intense shearing and melting, which might corresponds to an ancient seismogenic fault in the subduction boundary.