10:15 AM - 10:30 AM
[SCG56-06] Estimation of paleo-permeability around Nobeoka Thrust by application of permeability tensor theory to outcrop mineral veins
★Invited Papers
Keywords:Permeability, Crack, Mineral vein
Cracks exist in the bedrocks that could increase the permeability of the bedrocks since they act as water pathways of fluids. Once cracks filled with minerals and developed into mineral veins, they preserve the geometrical information of the past water pathways. In particular, the cracks formed by seismic events can provide hydraulic properties during seismic events (Otsubo et al., 2020; Saishu et al., 2017). Hosono et al. (2022) estimated paleo-permeability by measuring geometrical information of quartz veins in the footwall of the Nobeoka Thrust and applying the permeability tensor theory (Oda, 1985; Oda et al., 2002). The Nobeoka Thrust is the onshore analogue of the Out-of-Sequence Thrust, and is the past seismic fault (Okamoto et al., 2006). The displacement along the fault is estimated to be about 10 km based on the difference in maximum temperature between the hanging wall and footwall measured by vitrinite reflectance analyses.
The purpose of this study is to determine the values of three mutually perpendicular permeabilities (maximum, intermediate, and minimum permeabilities k1, k2, and k3) and their directions from the permeability tensor theory. In this presentation, we will outline the process from the observation of outcrops to the application of the permeability tensor theory, and discuss the results and future perspectives. The maximum permeability k1 varies over four times from 1.31×10-9m2 at the point 5 m from the fault core to 2.99×10-10m2at a point 80 m from the fault core. The maximum permeability k1 directed toward a high angle with the fault plane. The maximum permeability k1 is 1.8 to 2.6 times larger than the minimum permeability k3. This result indicates that there is permeability anisotropy around the fault during the seismic event.
References
Hosono, H., Takemura, T., Asahina, D., and Otsubo, M., 2022, Estimation of paleo-permeability around a seismogenic fault based on permeability tensor from observable geometric information of quartz veins: Earth, Planets and Space, v. 74, no. 1.
Oda, M., 1985, Permeability tensor for discontinuous rock masses: Géotechnique, v. 35, no. 4, p. 483-495.
Oda, M., Takemura, T., and Aoki, T., 2002, Damage growth and permeability change in triaxial compression tests of Inada granite: Mechanics of Materials, v. 34, no. 6, p. 313-331.
Okamoto, S., Kimura, G., Takizawa, S., and Yamaguchi, H., 2006, Earthquake fault rock indicating a coupled lubrication mechanism: eEarth Discussions, v. 1, no. 2, p. 135-149.
Otsubo, M., Hardebeck, J. L., Miyakawa, A., Yamaguchi, A., and Kimura, G., 2020, Localized fluid discharge by tensile cracking during the post-seismic period in subduction zones: Sci Rep, v. 10, no. 1, p. 12281.
Saishu, H., Okamoto, A., and Otsubo, M., 2017, Silica precipitation potentially controls earthquake recurrence in seismogenic zones: Sci Rep, v. 7, no. 1, p. 13337.
The purpose of this study is to determine the values of three mutually perpendicular permeabilities (maximum, intermediate, and minimum permeabilities k1, k2, and k3) and their directions from the permeability tensor theory. In this presentation, we will outline the process from the observation of outcrops to the application of the permeability tensor theory, and discuss the results and future perspectives. The maximum permeability k1 varies over four times from 1.31×10-9m2 at the point 5 m from the fault core to 2.99×10-10m2at a point 80 m from the fault core. The maximum permeability k1 directed toward a high angle with the fault plane. The maximum permeability k1 is 1.8 to 2.6 times larger than the minimum permeability k3. This result indicates that there is permeability anisotropy around the fault during the seismic event.
References
Hosono, H., Takemura, T., Asahina, D., and Otsubo, M., 2022, Estimation of paleo-permeability around a seismogenic fault based on permeability tensor from observable geometric information of quartz veins: Earth, Planets and Space, v. 74, no. 1.
Oda, M., 1985, Permeability tensor for discontinuous rock masses: Géotechnique, v. 35, no. 4, p. 483-495.
Oda, M., Takemura, T., and Aoki, T., 2002, Damage growth and permeability change in triaxial compression tests of Inada granite: Mechanics of Materials, v. 34, no. 6, p. 313-331.
Okamoto, S., Kimura, G., Takizawa, S., and Yamaguchi, H., 2006, Earthquake fault rock indicating a coupled lubrication mechanism: eEarth Discussions, v. 1, no. 2, p. 135-149.
Otsubo, M., Hardebeck, J. L., Miyakawa, A., Yamaguchi, A., and Kimura, G., 2020, Localized fluid discharge by tensile cracking during the post-seismic period in subduction zones: Sci Rep, v. 10, no. 1, p. 12281.
Saishu, H., Okamoto, A., and Otsubo, M., 2017, Silica precipitation potentially controls earthquake recurrence in seismogenic zones: Sci Rep, v. 7, no. 1, p. 13337.