HR: 1340h
AN: T23A-0562    [Abstracts]
TI: Frictional Properties of Feldspar Gouge Under High-Pressure and High-Temperature and Their Implications of Seismogenic Process
AU: * Masuda, K
EM: koji.masuda@aist.go.jp
AF: Institute of Geology and Geoinformation, Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (AIST), AIST Tsukuba Central 7, Tsukuba, 305-8567 Japan
AU: Arai, T
AF: National Institute of Technology and Evaluation (NITE), Shibuya, Tokyo, 151-0066 Japan
AU: Takahashi, M
AF: Institute of Geology and Geoinformation, Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (AIST), AIST Tsukuba Central 7, Tsukuba, 305-8567 Japan
AU: Fujimoto, K
AF: Tokyo Gakugei University, Koganei, Tokyo, 184-8501 Japan
AU: Shigematsu, N
AF: Chiba University, Inage, Chiba, 263-8522 Japan
AU: Kitamura, K
AF: Institute of Geology and Geoinformation, Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology (AIST), AIST Tsukuba Central 7, Tsukuba, 305-8567 Japan
AB: Understanding physical and chemical processes in the deep extensions of seismogenic fault zones is very important, since most of the main rupture of intraplate large earthquake starts at the base of the seismogenic zone. Geological studies on the exhumed fault zones, geophysical measurements of natural fault materials from seismogenic zones, and laboratory experimental studies under high-pressure and high-temperature conditions are carried out. Although it is essential to understand the mechanisms by which inland earthquakes occur and to establish physics-based forecast methods, the mechanism by which inland earthquakes occur is poorly understood in contrast to interpolate earthquakes. In order to understand the earthquake generation process, we need to understand the frictional and rheological properties of fault zone materials under high-pressure and high-temperature conditions. Laboratory data on frictional properties of fault surfaces of fault zone rocks are useful for understanding the slip process in deep extensions of seismogenic zones. Frictional properties of feldspar and quartz gouges under high-pressure and high-temperature conditions were obtained. In the laboratory study, we use the information on the natural fault materials based on the results of the geological study. We conducted geological studies on the exhumed seismogenic fault zone in Japan, the Hatagawa Fault Zone, to characterize fault zone materials and fault zone structure. We conducted frictional experiments (the velocity-stepping test) by using feldspar and quartz gouges (about 3 micron diameter) under high-pressure and high-temperature in the wet and dry conditions. Temperature varied from room temperature to 600C. 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. The values for a-b of quartz and feldspar were positive under the dry conditions from room temperature to 600C. On the other hand, in the wet conditions, velocity weakening of quartz gouge is seen at around 300C, and negative region is from 200C to 400C. Velocity weakening of feldspar gouge is observed from 150C to 450C in the wet conditions. Velocity weakening of feldspar gouge is more apparent than that of quartz gouge. If this is true, feldspar plays more important role than quartz, in the velocity weakening region observed with granite gouge. These frictional properties are discussed with the texture of samples by the SEM observations.
DE: 8010 Fractures and faults
DE: 8100 TECTONOPHYSICS
DE: 5100 PHYSICAL PROPERTIES OF ROCKS
DE: 7209 Earthquake dynamics and mechanics
DE: 7215 Earthquake parameters
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting