[S-CG55] Dynamics in mobile belts

[SCG55-P06] Surface topography of microcracks in a granitic rock

*Tohru Watanabe¹, Kenta Yoshida², Kenichiro Tani³ (1.Faculty of Sustainable Design, University of Toyama, 2.JAMSTEC, 3.National Museum of Nature and Science)

Keywords:microcrack, asperity, aperture, surface topography

Physical properties of intact rocks are strongly affected by the presence of microcracks. Microcracks have rough surfaces and asperities on them come into contact under pressure. The contacting asperities control the mechanical properties, and the resulting space between surfaces controls the transport properties. Though the surface topography of microcracks is important to understand the pressure dependence of physical properties, it is still poorly understood. We have studied the surface structure of microcracks in Aji granite (Kagawa Pref.) by using a dual-beam focused ion beam-SEM (FIB-SEM). A grayscale image was binarized to yield a black and white image, and then the asperity height and aperture were measured. Since most cracks in Aji granite are open grain boundaries, we have also studied the surface topography of quartz grains by using an optical profilometer. The quartz grains were extracted from a rock sample through the selective fragmentation (SELFRAG) using high voltage pulsed power. We will present characteristics of the observed surface topography of microcracks and quartz grains. Results of numerical experiments on the crack closure will be also presented.