Abstract
Samples of damage-zone granodiorite and fault core from two drillholes into the active, strikeslip Nojima fault zone display microstructures and alteration features that explain their measured present-day strengths and permeabilities and provide insight on the evolution of these properties in the fault zone. The least deformed damage-zone rocks contain two sets of nearly perpendicular (60–90° angles), roughly vertical fractures that are concentrated in quartz-rich areas, with one set typically dominating over the other. With increasing intensity of deformation, which corresponds generally to increasing proximity to the core, zones of heavily fragmented rock, termed microbreccia zones, develop between prominent fractures of both sets. Granodiorite adjoining intersecting microbreccia zones in the active fault strands has been repeatedly fractured and locally brecciated, accompanied by the generation of millimeter-scale voids that are partly filled with secondary minerals. Minor shear bands overprint some of the heavily deformed areas, and small-scale shear zones form from the pairing of closely spaced shear bands. Strength and permeability measurements were made on core collected from the fault within a year after a major (Kobe) earthquake. Measured strengths of the samples decrease regularly with increasing fracturing and fragmentation, such that the gouge of the fault core and completely brecciated samples from the damage zone are the weakest. Permeability increases with increasing disruption, generally reaching a peak in heavily fractured but still more or less cohesive rock at the scale of the laboratory samples. Complete loss of cohesion, as in the gouge or the interiors of large microbreccia zones, is accompanied by a reduction of permeability by 1–2 orders of magnitude below the peak values. The core samples show abundant evidence of hydrothermal alteration and mineral precipitation. Permeability is thus expected to decrease and strength to increase somewhat in active fault strands between earthquakes, as mineral deposits progressively seal fractures and fill pore spaces.
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References
Awata, Y., and Suzuki, Y. (1996), Paleoseismology and activity study of the Nojima fault system, which generated the Hyogo-ken Nanbu earthquake of January 17, 1995, Geol. Surv. Japan Open-File Report 250, 4–8 (in Japanese).
Awata, Y., Mizuno, K., Sugiyama, Y., Imura, R., Shimokawa, K., Okumura, K., and Tsukuda, E. (1996), Surface fault ruptures on the northwest coast of Awaji Island associated with the Hyogoken Nanbu earthquake of 1995, J. Seismol. Soc. Japan 49, 113–124 (in Japanese with English abstract).
Boullier, A.-M., Fujimoto, K., Ohtani, T., Roman-Ross, G., Lewin, E., Ito, H., Pezard, P., and Idlefonse, B. (2004), Textural evidence for recent co-seismic circulation of fluids in the Nojima fault zone, Awaji island, Japan, Tectonophysics 378, 165–181.
Caine, J.S., Evans, J.P., and Forster, C.B. (1996), Fault zone architecture and permeability structure, Geology 24, 1025–1028.
Célérier, B.P., Pezard, P.A., Ito, H., and Kiguchi, T. (2000), Borehole wall geometry across the Nojima fault: BHTV acoustic scans analysis from the GSJ Hirabayashi hole, Japan. In The International Workshop on the Nojima Fault Core and Borehole Data Analysis (eds. Ito, H., Fujimoto, K., Tanaka, H., and Lockner, D.), U.S. Geol. Surv. Open-File Report 00-129, pp. 233–238.
Chester, F.M., and Logan, J.M. (1986), Implications for mechanical properties of brittle faults from observations of the Punchbowl fault zone, California. In Internal Structure of Fault Zones (ed. Wang, C.-Y.), Pure Appl. Geophys. 124, 79–106.
Chester, F.M., Evans, J.P., and Biegel, R.L. (1993), Internal structure and weakening mechanisms of the San Andreas fault, J. Geophys. Res. 98, 771–786.
Fujimoto, K., Tanaka, H., Tomida, N., Ohtani, T., and Ito, H. (2000), Characterization of fault gouge from GSJ Hirabayashi core samples and implications for the activity of the Nojima fault. In The International Workshop on the Nojima Fault Core and Borehole Data Analysis (eds. Ito, H., Fujimoto, K., Tanaka, H., and Lockner, D.), U. S. Geol. Surv. Open-File Report 00-129, pp. 103–109.
Fujimoto, K., Ueda, A., Ohtani, T., Takahashi, M., Ito, H., Tanaka, H., and Boullier, A.-M. (2007), Borehole water and hydrologic model around the Nojima fault, SW Japan, Tectonophysics 443, 174–182.
Ikeda, R. (2001), Outline of the fault zone drilling project by NIED in the vicinity of the 1995 Hyogo-ken Nanbu earthquake, Japan, Island Are 10, 199–205.
Ikeda, R., Ito, Y., and Omura, K. (2001), In situ stress measurements in NIED boreholes in and around the fault zone near the 1995 Hyogo-ken Nanbu earthquake, Japan, Island Are 10, 252–260.
King, G.C.P., and Sammis, C.G. (1992), The mechanics of finite brittle strain, Pure Appl. Geophys. 138, 611–640.
Lin, A., and Uda, S. (1996), Morphological characteristics of the earthquake surface rupture which occurred on Awaji Island, associated with the 1995 southern Hyogo Prefecture earthquake, Island Arc 5, 1–5.
Lin, A., Shimamoto, T., Maruyama, T., Sigetomi, M., Miyata, T., Takemura, K., Tanaka, H., Uda, S., and Murata, A. (2001), Comparative study of cataclastic rocks from a drill core and outcrops of the Nojima Fault zone on Awaji Isand, Japan. Island Arc 10, 368–380.
Lockner, D., Naka, H., Tanaka, H., Ito, H., Ikeda, R., and Omura, K. (2009), Geometry of the Nojima fault at Nojima-Hirabayashi, Japan — I. A simple damage structure inferred from borehole core permeability, this volume.
Matsuda, T., Omura, K., Ikeda, R., Arai, T., Kobayashi, K., Shimada, K., Tanaka, H., Tomita, T., and Hirano, S. (2004), Fracture-zone conditions on a recently active fault: Insights from mineralogical and geochemical analyses of the Hirabayashi NIED drill core on the Nojima fault, southwest Japan, which ruptured in the 1995 Kobe earthquake, Tectonophysics 378, 143–163.
Mizuno, K., Hattori, H., Sangawa, A., and Takahashi, Y. (1990), Geology of the Akashi district, quadrangle series, Geol. Surv. Japan, scale 1:50,000, 90 pp. (in Japanese with English abstract).
Moore, D.E. (1987), Syndeformational metamorphic myrmekite in granodiorite of the Sierra Nevada, California, Geol. Soc. Am. Abstr. with Progr. 19(7), 776.
Moore, D.E. (1990), Flame perthite associated with faulting in granodiorite. Mt. Abbot quadrangle, California, EOS, Trans. Am. Geophys. Union 71, 1596.
Moore, D.E., and Lockner, D.A. (1995), The role of microcracking in shear-fracture propagation in granite, J. Struct. Geol. 17, 95–114.
Moore, D.E., and Lockner, D.A. (2004), Crystallographic controls on the frictional behavior of dry and watersaturated sheet structure minerals, J. Geophys. Res. 109, B03401, doi: 10.1029/2003JB002582.
Moore, D.E., Hickman, S., Lockner, D.A., and Dobson, P.F. (2001), Hydrothermal minerals and microstructures in the Silangkitang geothermal field along the Great Sumatran fault zone, Sumatra, Geol. Soc. Am. Bull. 113, 1179–1192.
Moore, D.E., Lockner, D.A., Ito, H., and Ikeda, R. (2000), Carbonate mineralization sequence and the earthquake history of the Nojima fault zone, Japan, EOS, Trans. Am. Geophys. Union 81, F1099–F1100.
Morrow, C.A., and Byerlee, J.D. (1991), A note on the frictional strength of laumontite from Cajon Pass, California, Geophys. Res. Lett. 18, 211–214.
Morrow, C., Lockner, D., Hickman, S., Rusanov, M., and Röckel, T. (1994), Effects of lithology and depth on the permeability of core samples from the Kola and KTB drill holes, J. Geophys. Res. 99, 7263–7274.
Morrow, C.A., Moore, D.E., and Lockner, D.A. (2000), The effect of mineral bond strength and adsorbed water on fault gouge frictional strength, Geophys. Res. Lett. 27, 815–818.
Murakami, M., and Tagami, T. (2004), Dating pseudotachylyte of the Nojima fault using the zircon fission-track method, Geophys. Res. Lett. 31, L12604, doi:10.1029/2004GL020211.
Murata, A., Takemura, K., Miyata, T., and Lin, A. (2001), Quaternary vertical offset and average slip rate of the Nojima Fault on Awaji Island, Japan, Island Arc 10, 360–367.
Ohtani, T., Fujimoto, K., Ito, H., Tanaka, H., Tomida, N., and Higuchi, T. (2000), Fault rocks and past to recent fluid characteristics from the borehole survey of the Nojima fault ruptured in the 1995 Kobe earthquake, southwest Japan, J. Geophys. Res. 105, 16,161–16,171.
Otsuki, K., Monzawa, N., and Nagase, T. (2003), Fluidization and melting of fault gouge during seismic slip: Identification in the Nojima fault zone and implications for focal earthquake mechanisms, J. Geophys. Res. 108, B4, 2192, doi:10.1029/2001JB001711.
Seno, T. (1999), Syntheses of the regional stress field of the Japanese islands, Island Are 8, 66–79.
Streckeisen, A. (1974), Classification and nomenclature of plutonic rocks, Geol. Rundschau 63, 773–785.
Tagami, T., and Murakami, M. (2007), Probing fault zone heterogeneity on the Nojima fault: Constraints from zircon fission-track analysis of borehole samples, Tectonophysics 443, 139–152.
Takahashi, Y. (1992), K-Ar ages of the granitic rocks in Awaji Island — with an emphasis on timing of mylonitization, Gankou 87, 291–299 (in Japanese with English abstract).
Takeshita, T., and Yagi, K. (2000), Dynamic analysis based on 3-D orientation distribution of microcracks in quartz from the Cretaceous granodiorite core samples drilled along the Nojima fault, southwest Japan. In The International Workshop on the Nojima Fault Core and Borehole Data Analysis (eds. Ito, H., Fujimoto, K., Tanaka, H., and Lockner, D.), U. S. Geol. Surv. Open-File Report 00-129, pp. 133–140.
Takeshita, T., and Yagi, K. (2001), Paleostress orientation from 3-D orientation distribution of microcracks in quartz from the Cretaceous granodiorite core samples drilled through the Nojima fault, southwest Japan, Island Arc 10, 495–505.
Tanaka, H., Fujimoto, K., Ohtani, T., and Ito, H. (2001), Structural and chemical characterization of shear zones in the freshly activated Nojima fault, Awaji Island, southwest Japan, J. Geophys. Res. 106, 8789–8810.
Tanaka, H., Omura, K., Matsuda, T., Ikeda, R., Kobayashi, K., Murakami, M., and Shimada, K. (2007), Architectural evolution of the Nojima fault and identification of the activated slip layer by Kobe earthquake, J. Geophys. Res. 112, B07304, doi:10.1029/2005JB003977.
Vollbrecht, A., Rust, S., and Weber, K. (1991), Development of microcracks in granites during cooling and uplift: Examples from the Variscan basement in NE Bavaria, Germany, J. Struct. Geol. 13, 787–799.
Wong, T.-F. (1982), Micromechanics of faulting in Westerly granite, Int. J. Rock Mech. Mining Sci. Geomech. Abstr. 19, 49–64.
Yamamoto, K., Sato, N., and Yabe, Y. (2000), Stress state around the Nojima fault estimated from core measurements. In The International Workshop on the Nojima Fault Core and Borehole Data Analysis (eds. Ito, H., Fujimoto, K., Tanaka, H., and Lockner, D.), U. S. Geol. Surv. Open-File Report 00–129, pp. 239–246.
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Moore, D.E., Lockner, D.A., Ito, H., Ikeda, R., Tanaka, H., Omura, K. (2009). Geometry of the Nojima Fault at Nojima-Hirabayashi, Japan — II. Microstructures and their Implications for Permeability and Strength. In: Ben-Zion, Y., Sammis, C. (eds) Mechanics, Structure and Evolution of Fault Zones. Pageoph Topical Volumes. Birkhäuser Basel. https://doi.org/10.1007/978-3-0346-0138-2_7
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