Japan Geoscience Union Meeting 2014

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Oral

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

[S-SS32_1AM1] Fault Rheology and Earthquake Dynamics

Thu. May 1, 2014 9:00 AM - 10:45 AM 315 (3F)

Convener:*Kiyokazu Oohashi(Graduate School of Science, Chiba University), Takeshi Iinuma(International Research Institute of Disaster Science, Tohoku University), Wataru Tanikawa(Japan Agency for Marine-Earth Science and Technology, Kochi Instutute for Core Sample Research), Yuta Mitsui(Department of Geosciences, Graduate School of Science, Shizuoka University), Chair:Kiyokazu Oohashi(Graduate School of Science, Chiba University), Yuta Mitsui(Department of Geosciences, Graduate School of Science, Shizuoka University)

9:30 AM - 9:45 AM

[SSS32-03] Physico-chemo-mechanical processes in a slip zone during the 1999 Taiwan Chi-Chi earthquake

*Tetsuro HIRONO1, Jun KAMEDA2, Hiroki KANDA1, Wataru TANIKAWA3, Tsuyoshi ISHIKAWA3 (1.Osaka Univ., 2.Hokkaido Univ., 3.JAMSTEC)

Keywords:mechanochemical, amorphous

To investigate the physicochemical processes of minerals during and after slip of the 1999 Taiwan Chi-Chi earthquake, we analyzed the mineral assemblages in the Chelungpu fault by using quantitative X-ray diffraction together with scanning and transmission electron microscope observations. In the primary slip zone, we found markedly low contents of quartz and clay minerals and large amounts of amorphous particles ranging in size from submicrometer to several tens of nanometers. Milling and heating experiments with host-rock samples indicated that these mineralogical changes are due to comminution and frictional heat during slip. Moreover, the changes may affect slip behavior through a mechanism such as thermal pressurization assisted by clay-mineral dehydration. In addition, preservation of a high amount of amorphous fine particles can potentially be used to identify the slip zone of the latest earthquake on not only the Chelungpu fault but also on other faults.