[S-SS32_1AM1] 断層帯のレオロジーと地震の発生過程

[SSS32-03] 1999年台湾集集地震時におけるスリップゾーンでの物理-化学-メカニカルプロセス

*廣野 哲朗¹、亀田 純²、神田 大樹¹、谷川 亘³、石川 剛志³ (1.大阪大学、2.北海道大学、3.海洋研究開発機構)

キーワード：メカノケミカル, アモルファス

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.