The Effect of Clay Content on the Dilatancy and Frictional Properties of Fault Gouge

Ashman, Isabel; Faulkner, Daniel R.

doi:10.1029/2022jb025878

Cited by 16 publications

(10 citation statements)

References 81 publications

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“…Our observations conducted in initially intact rock are directly relevant to rupture and slip in "immature" fault systems, or faults that have been substantially sealed or healed during the interseismic period. In more "mature" fault rocks containing clay-rich gouges, dilatancy is also significant (e.g., Ashman & Faulkner, 2023), and we expect a similar qualitative behavior to that observed in intact rocks, albeit with different magnitudes for fluid pressure drops.…”

Section: Implications and Upscalingsupporting

confidence: 68%

Rupture and Afterslip Controlled by Spontaneous Local Fluid Flow in Crustal Rock

Aben,

Brantut

2023

JGR Solid Earth

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Shear rupture and fault slip in crystalline rocks like granite produce large dilation, impacting the spatiotemporal evolution of fluid pressure in the crust during the seismic cycle. To explore how fluid pressure variations are coupled to rock deformation and fault slip, we conducted laboratory experiments under upper crustal conditions while monitoring acoustic emissions and in situ fluid pressure. Our results show two separate faulting stages: initial rupture propagation, associated with large dilatancy and stabilized by local fluid pressure drops, followed by sliding on the newly formed fault, promoted by local fluid pressure recharge from the fault walls. This latter stage had not been previously recognised and can be understood as fluid‐induced afterslip, co‐located with the main rupture patch. Upscaling our laboratory results to the natural scale, we expect that spontaneous fault zone recharge could be responsible for early afterslip in locally dilating regions of major crustal faults, independently from large‐scale fluid flow patterns.

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Section: Implications and Upscalingsupporting

confidence: 68%

Rupture and Afterslip Controlled by Spontaneous Local Fluid Flow in Crustal Rock

Aben,

Brantut

2023

JGR Solid Earth

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“…Fluid pressurization of the fracture requires injection of fluid volume from the pump, according to the compression‐induced pressurization principle of fluids (Ji, Kluge, et al., 2022; Kestin, 1979). Particularly, the elevation of fluid pressure is linearly correlated with the increase of injected fluid volume when the sample volume is constant, and thus any changes in sample volume result in variations of the injected fluid volume (cf., Ashman & Faulkner, 2023; Samuelson et al., 2009). The slip displacement starts to increase when the fluid pressure reaches the critical activation fluid pressure.…”

Section: Resultsmentioning

confidence: 99%

Fracture Permeability Enhancement During Fluid Injection Modulated by Pressurization Rate and Surface Asperities

Ji,

Zhang,

Hofmann

et al. 2023

Geophysical Research Letters

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We present a series of controlled fluid injection experiments in the laboratory on a pre‐stressed natural rough fracture with a high initial permeability (∼10−13 m2) in granite using different fluid pressurization rates. Our results show that fluid injection on a fracture with a slight velocity‐strengthening frictional behavior exhibits dilatant slow slip in association with a permeability increase up to ∼41 times attained at the maximum slip velocity of 0.085 mm/s for the highest‐rate injection case. Under these conditions, the slip velocity‐dependent change in hydraulic aperture is a dominant process to explain the transient evolution of fracture permeability, which is modulated by fluid pressurization rate and fracture surface asperities. This leads to the conclusion that permeability evolution can be engineered for subsurface geoenergy applications by controlling the fluid pressurization rate on slowly slipping fractures.

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“…Grain comminution is associated with widening of the particle‐size distribution, which in turn can inhibit dilatation (Bedford & Faulkner, 2021; Ferdowsi & Rubin, 2020; Guo & Morgan, 2006; Mair et al., 2002). Indeed, mature faults, for which variations in particle size may exceed four orders of magnitude (Chester et al., 2005), and clayey ultracataclastic gouges exhibit reduced dilatation (Ashman & Faulkner, 2023; Delle Piane et al., 2017; Mair & Marone, 1999). Present results neglecting grain comminution and using a narrow grain size distribution are therefore relevant rather for relatively young faults with small accumulated displacement or for a rupture of fresh rock.…”

Section: Discussionmentioning

confidence: 99%

Pore Pressure Drop During Dynamic Rupture and Conditions for Dilatancy Hardening

2023

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Geological faults are often saturated with fluids. Pore fluid pressure controls fault strength and stability of slip. The effect of pore fluid pressure, P, on the shear strength, τ, is commonly expressed by the effective stress law (Hubbert & Rubey, 1959)where μ is the friction coefficient, and σ n is fault-normal (tectonic) stress. Increasing pore pressure reduces the effective normal stress, 𝐴𝐴 𝐴𝐴 ′ n = 𝐴𝐴n − 𝑃𝑃 , and thus the resistance to sliding. Fluid-induced changes in the effective stress have been invoked to explain the earthquake cycle (R.

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The Effect of Clay Content on the Dilatancy and Frictional Properties of Fault Gouge

Abstract: The presence of clay minerals has the potential to influence the seismic cycle, and earthquake nucleation in particular, through the frictional strength and stability of the gouge, and pore fluid pressure changes resulting from dilation or compaction during slip velocity transients (

Cited by 16 publications

References 81 publications

Rupture and Afterslip Controlled by Spontaneous Local Fluid Flow in Crustal Rock

Rupture and Afterslip Controlled by Spontaneous Local Fluid Flow in Crustal Rock

Fracture Permeability Enhancement During Fluid Injection Modulated by Pressurization Rate and Surface Asperities

Pore Pressure Drop During Dynamic Rupture and Conditions for Dilatancy Hardening

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