HR: 1330h
AN: S22A-0429    [PDF]
TI: Frictional Properties of Feldspar and Quartz at the Temperatures of Seismogenic Zone
AU: * Arai, T
EM: t.arai@aist.go.jp
AF: Geological Survey of Japan/AIST, Institute of Geoscience, AIST Tsukuba Central 7, Tsukuba, 305-8567 Japan
AU: Masuda, K
EM: koji.masuda@aist.go.jp
AF: Geological Survey of Japan/AIST, Institute of Geoscience, AIST Tsukuba Central 7, Tsukuba, 305-8567 Japan
AU: Takahashi, M
AF: Geological Survey of Japan/AIST, Institute of Geoscience, AIST Tsukuba Central 7, Tsukuba, 305-8567 Japan
AU: Fujimoto, K
AF: Geological Survey of Japan/AIST, Institute of Geoscience, AIST Tsukuba Central 7, Tsukuba, 305-8567 Japan
AU: Shigematsu, N
AF: Geological Survey of Japan/AIST, Institute of Geoscience, AIST Tsukuba Central 7, Tsukuba, 305-8567 Japan
AU: Sumii, T
AF: Geological Survey of Japan/AIST, Institute of Geoscience, AIST Tsukuba Central 7, Tsukuba, 305-8567 Japan
AU: Okuyama, Y
AF: Geological Survey of Japan/AIST, Institute of Geoscience, AIST Tsukuba Central 7, Tsukuba, 305-8567 Japan
AB: Most of earthquakes in the crust occurred at the depth of 5 to 20km, and temperatures of 100 to $350\deg$C. The physical properties of rocks at around these temperatures were determined by many frictional experiments. These results indicated the velocity dependence of steady state friction $(a-b)$ was switched from velocity weakening $($ seismic slip $)$ to velocity strengthening $($ aseismic slip $)$ at around $350\deg$C in the wet condition. In these experimental studies, granites were generally used. On the other hand, it is important to evaluate and to compare the physical properties of each mineral which composed of crustal rocks, for example feldspar and quartz, in order to understand the source processes of earthquakes in detail. In this study, we conducted frictional experiments by using albite, anorthite, and quartz gouges $($ about 3$\mu$m diameter $)$ under high pressure and high temperature in a triaxial apparatus, and compared frictional behaviors of three minerals with elevated temperature under the wet and dry conditions. These experiments were conducted by the velocity-stepping test. Temperature varied from room temperature to $600\deg$C. In the dry conditions, experiments were conducted under the confining pressure of 150MPa. In the wet conditions, pore water pressure was applied up to 50MPa under the confining pressure of 200MPa. Sample was put between upper and lower sawcut alumina cylinders $($ 20mm diameter $\times$ 40mm long $)$. The sawcut was oriented at $30\deg$ to the loading axis. These were jacketed with thin sleeves of annealed Cu. The values for a-b of quartz and albite were positive under the dry condition from room temperature to $600\deg$C. On the other hand, those values of albite and quartz were negative at the temperature of $200\deg$C and $300\deg$C under the wet condition respectively. Those values of quartz decreased as the temperature increased from $100\deg$C to $300\deg$C and increased as the temperature increased from $300\deg$C to $600\deg$C. Those values of albite were switched from velocity weakening to velocity strengthening between the temperature of $200\deg$C and $300\deg$C, and increased in the temperature range up to $600\deg$C. The frictional coefficient of albite decreased gradually not exponentially after velocity-step from the temperature of $250\deg$C to $350\deg$C. We will discuss these frictional properties with the texture of samples by the SEM observations.
DE: 1242 Seismic deformations (7205)
DE: 5100 PHYSICAL PROPERTIES OF ROCKS
DE: 5475 Tectonics (8149)
DE: 7209 Earthquake dynamics and mechanics
DE: 7215 Earthquake parameters
SC: Seismology [S]
MN: 2003 Fall Meeting