Variations in stress and driving pore fluid pressure ratio using vein orientations along megasplay faults : Example from the Nobeoka Thrust, Southwest Japan

Island Arc ◽  
2016 ◽  
Vol 25 (6) ◽  
pp. 421-432 ◽  
Author(s):  
Makoto Otsubo ◽  
Ayumu Miyakawa ◽  
Ryoji Kawasaki ◽  
Katsushi Sato ◽  
Asuka Yamaguchi ◽  
...  
Keyword(s):  
Pressure Ratio ◽  
Fluid Pressure ◽  
Pore Fluid ◽  
Southwest Japan ◽  
Pore Fluid Pressure

Temporal changes in pore fluid pressure during slow earthquake cycle estimated from foliation-parallel extension cracking

2021 ◽  
Author(s):  
Makoto Otsubo ◽  
Kohtaro Ujiie ◽  
Hanae Saishu ◽  
Ayumu Miyakawa ◽  
Asuka Yamaguchi
Keyword(s):  
Quartz Vein ◽  
Pressure Ratio ◽  
Fluid Pressure ◽  
Pore Fluid ◽  
Lithostatic Pressure ◽  
Mode I ◽  
Pore Fluid Pressure ◽  
Slow Earthquake ◽  
Vein Formation ◽  
Parallel Extension

<p>Pore fluid pressure (P<sub>f</sub>) is of great importance to understand slow earthquake mechanics. In this study, we estimated the pore fluid pressure during the formation of foliation-parallel quartz veins filling mode I cracks in the Makimine mélange eastern Kyushu, SW Japan. The mélange preserves quartz-filled shear veins, foliation-parallel extension veins and subvertical extension tension vein arrays. The coexistence of the crack-seal veins and viscously sheared veins (aperture width of a quartz vein: a few tens of microns) may represent episodic tremor and slow slip (Ujiie et al., 2018). The foliation-parallel extension cracks can function as the fluid pathway in the mélange. We applied the stress tensor inversion approach proposed by Sato et al. (2013) to estimate stress regimes by using foliation-parallel extension vein orientations. The estimated stress is a reverse faulting stress regime with a sub-horizontal σ<sub>1</sub>-axis trending NNW–SSE and a sub-vertical σ<sub>3</sub>-axis, and the driving pore fluid pressure ratio P* (P* = (P<sub>f</sub> – σ<sub>3</sub>) / (σ<sub>1</sub> – σ<sub>3</sub>)) is ~0.1. When the pore fluid pressure exceeds σ<sub>3</sub>, veins filling mode I cracks are constructed (Jolly and Sanderson, 1997). The pore fluid pressure that exceeds σ<sub>3</sub> is the pore fluid overpressure ΔP<sub>f</sub> (ΔP<sub>f</sub> = P<sub>f</sub> – σ<sub>3</sub>). To estimate the pore fluid overpressure, we used the poro-elastic model for extension quartz vein formation (Gudmundsson, 1999). P<sub>f</sub> and ΔP<sub>f</sub> in the case of the Makimine mélange are ~280 MPa and 80–160 kPa (assuming depth = 10 km, density = 2800 kg/m<sup>3</sup>, tensile strength = 1 MPa and Young’s modulus = 7.5–15 GPa). When the pore fluid overpressure is released, the cracks are closed and the reduction of pore fluid pressure is stopped (Otsubo et al., 2020). After the pore fluid overpressure is reduced, the normalized pore pressure ratio λ* (λ* = (P<sub>f</sub> – P<sub>h</sub>) / (P<sub>l</sub> – P<sub>h</sub>), P<sub>l</sub>: lithostatic pressure; P<sub>h</sub>: hydrostatic pressure) is ~1.01 (P<sub>f</sub> > P<sub>l</sub>). The results indicate that the pore fluid pressure constantly maintains the lithostatic pressure during the extension cracking along the foliation.</p><p>References: Gudmundsson (1999) Geophys. Res. Lett., 26, 115–118; Jolly and Sanderson (1997) Jour. Struct. Geol., 19, 887–892; Otsubo et al. (2020) Sci. Rep., 10:12281; Palazzin et al. (2016) Tectonophysics, 687, 28–43; Sato et al. (2013) Tectonophysics, 588, 69–81; Ujiie et al. (2018) Geophys. Res. Lett., 45, 5371–5379, https://doi.org/10.1029/2018GL078374.</p>

scholarly journals Correction to: Stress and pore fluid pressure control of seismicity rate changes following the 2016 Kumamoto earthquake, Japan

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Kodai Nakagomi ◽  
Toshiko Terakawa ◽  
Satoshi Matsumoto ◽  
Shinichiro Horikawa
Keyword(s):  
Fluid Pressure ◽  
Pressure Control ◽  
Pore Fluid ◽  
2016 Kumamoto Earthquake ◽  
Pore Fluid Pressure ◽  
Seismicity Rate ◽  
Kumamoto Earthquake ◽  
The 2016 Kumamoto Earthquake ◽  
Seismicity Rate Changes

An amendment to this paper has been published and can be accessed via the original article.

scholarly journals Fracture-induced pore fluid pressure weakening and dehydration of serpentinite

2019 ◽  
Vol 767 ◽  
pp. 228168 ◽  
Author(s):  
Melodie E French ◽  
Greg Hirth ◽  
Keishi Okazaki
Keyword(s):  
Fluid Pressure ◽  
Pore Fluid ◽  
Pore Fluid Pressure

scholarly journals Control of pore fluid pressure diffusion on fault failure mode: Insights from the 2009 L'Aquila seismic sequence

2012 ◽  
Vol 117 (B5) ◽  
pp. n/a-n/a ◽  
Author(s):  
Luca Malagnini ◽  
Francesco Pio Lucente ◽  
Pasquale De Gori ◽  
Aybige Akinci ◽  
Irene Munafo'
Keyword(s):  
Failure Mode ◽  
Fluid Pressure ◽  
Pore Fluid ◽  
Seismic Sequence ◽  
Pore Fluid Pressure ◽  
Pressure Diffusion

Connections between subducted sediment, pore-fluid pressure, and earthquake behavior along the Alaska megathrust

Geology ◽  
2018 ◽  
Vol 46 (4) ◽  
pp. 299-302 ◽  
Author(s):  
Jiyao Li ◽  
Donna J. Shillington ◽  
Demian M. Saffer ◽  
Anne Bécel ◽  
Mladen R. Nedimović ◽  
...  
Keyword(s):  
Fluid Pressure ◽  
Pore Fluid ◽  
Pore Fluid Pressure ◽  
Subducted Sediment
Sign in / Sign up

Export Citation Format

Share Document