On the importance of normal vibrations in modeling of stick slip in rock sliding

Tworzydlo, W. W.; Hamzeh, Osama N.

doi:10.1029/97jb01167

Cited by 33 publications

(7 citation statements)

References 36 publications

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“…Figure 3 shows a typical trajectory of the friction stress in slip and slip rate space. We choose to specify the friction explicitly in terms of stresses and independent of the fault normal stress, because dynamic changes in friction during slip may be independent of the overburden pressure as a result of dynamic processes [see, e.g., Brune et al , 1993; Melosh , 1996; Tworzydlo and Hamzeh , 1997; Brodsky and Kanamori , 2001].…”

Section: Methodsmentioning

confidence: 99%

Constraining fault constitutive behavior with slip and stress heterogeneity

Aagaard

Heaton

2008

J. Geophys. Res.

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[1] We study how enforcing self-consistency in the statistical properties of the preshear and postshear stress on a fault can be used to constrain fault constitutive behavior beyond that required to produce a desired spatial and temporal evolution of slip in a single event. We explore features of rupture dynamics that (1) lead to slip heterogeneity in earthquake ruptures and (2) maintain these conditions following rupture, so that the stress field is compatible with the generation of aftershocks and facilitates heterogeneous slip in subsequent events. Our three-dimensional finite element simulations of magnitude 7 events on a vertical, planar strike-slip fault show that the conditions that lead to slip heterogeneity remain in place after large events when the dynamic stress drop (initial shear stress) and breakdown work (fracture energy) are spatially heterogeneous. In these models the breakdown work is on the order of MJ/m 2 , which is comparable to the radiated energy. These conditions producing slip heterogeneity also tend to produce narrower slip pulses independent of a slip rate dependence in the fault constitutive model. An alternative mechanism for generating these confined slip pulses appears to be fault constitutive models that have a stronger rate dependence, which also makes them difficult to implement in numerical models. We hypothesize that self-consistent ruptures could also be produced by very narrow slip pulses propagating in a self-sustaining heterogeneous stress field with breakdown work comparable to fracture energy estimates of kJ/M 2 .Citation: Aagaard, B. T., and T. H. Heaton (2008), Constraining fault constitutive behavior with slip and stress heterogeneity,

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Section: Methodsmentioning

confidence: 99%

Constraining fault constitutive behavior with slip and stress heterogeneity

Aagaard

Heaton

2008

J. Geophys. Res.

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“…Whereas the friction models and the variation of the parameters with the material properties and the depth are not based on a particular mechanism for the sliding friction, a number of mechanisms have been proposed for low levels of dynamic friction during earthquakes (Brune et al, 1993;Melosh, 1996;Harris and Day, 1997;Sleep, 1997;Tworzydlo and Hamzeh, 1997;Ben-Zion and Andrews, 1998;Anooshehpoor and Brune, 1999;Brodsky and Kanamori, 2001). A combination of such mechanisms may produce a complex variation in the effective coefficient of friction over the depth of the fault during sliding, which resembles our ad hoc variation.…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, stateand rate-dependent friction models imply high-sliding friction in the presence of large fault normal compressive stresses. Several plausible mechanisms have been suggested to explain why friction varies in both space and time during earthquakes for dynamic reasons, for example, wrinklelike slip pulses associated with a contrast in material properties (Harris and Day, 1997;Ben-Zion and Andrews, 1998;Anooshehpoor and Brune, 1999), acoustic fluidization (Melosh, 1996), normal vibrations (Brune et al, 1993;Tworzydlo and Hamzeh, 1997), and elastohydrodynamic lubrication (Brodsky and Kanamori, 2001). Instead of choosing to model any particular mechanism, we approximate the general features of the behaviors with simple friction models because several of these mechanisms may be combining to change the friction stress during sliding.…”

Section: Friction Modelsmentioning

confidence: 99%

Dynamic Earthquake Ruptures in the Presence of Lithostatic Normal Stresses: Implications for Friction Models and Heat Production

Aagaard¹

2001

Bulletin of the Seismological Society of America

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We simulate dynamic ruptures on a strike-slip fault in homogeneous and layered half-spaces and on a thrust fault in a layered half-space. With traditional friction models, sliding friction exceeds 50% of the fault normal compressive stress, and unless the pore pressures approach the lithostatic stress, the rupture characteristics depend strongly on the depth, and sliding generates large amounts of heat. Under application of reasonable stress distributions with depth, variation of the effective coefficient of friction with the square root of the shear modulus and the inverse of the depth creates distributions of stress drop and fracture energy that produce realistic rupture behavior. This ad hoc friction model results in (1) low-sliding friction at all depths and (2) fracture energy that is relatively independent of depth. Additionally, friction models with rate-weakening behavior (which form pulselike ruptures) appear to generate heterogeneity in the distributions of final slip and shear stress more effectively than those without such behavior (which form cracklike ruptures). For surface rupture on a thrust fault, the simple slip-weakening friction model, which lacks rate-weakening behavior, accentuates the dynamic interactions between the seismic waves and the rupture and leads to excessively large ground motions on the hanging wall. Waveforms below the center of the fault (which are associated with waves radiated to teleseismic distances) indicate that source inversions of thrust events may slightly underestimate the slip at shallow depths.

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“… Bureau et al [2000] and Cochard et al [2003] studied the effect of high frequency normal load vibrations and found that even a modest modulation induced substantial frictional weakening. Tworzydlo and Hamzeh [1997] noted that the inclusion of normal force vibrations in models of rock friction can cause instability. Theoretically, Perfettini et al [2001] identified a resonant response of shear zone strength, involving strong amplification of the shear stress and velocity response for a small range of friction parameters and a critical loading stiffness.…”

Section: Introductionmentioning

confidence: 99%

Effects of normal stress perturbations on the frictional properties of simulated faults

Hong

Marone

2005

Geochem Geophys Geosyst

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[1] We report on laboratory experiments to investigate the frictional response of creeping faults to sudden changes in normal stress. Experiments were conducted on layers of quartz powder, bare surfaces of Westerly granite, and layers of a 50/50 mixture of quartz powder and smectite clay powder. The tests were carried out at room temperature and controlled humidity using a servo-controlled double-direct shear configuration. Normal stress perturbations, corresponding to loading and unloading of tectonic fault zones, were applied during steady sliding at constant loading rate from 3 to 1000 mm/s (shear strain rates of 1.5 Â 10 À3 to 0.5 s À1 ). Sudden changes in normal stress resulted in a linear elastic response of shear stress followed by a transient evolution of friction over a characteristic displacement. The transient, inelastic response is quantified as a = (Dt a /s)/ln(s/s 0 ), where Dt a is the transient change in shear stress following a step change from initial normal stress s 0 to final normal stress s. We find that a is independent of sliding velocity and varies with ambient relative humidity and shear loading history. For unloading, we document a transition from stable to unstable behavior as a function of net slip in the range 3 to 30 mm (shear strains of 1.5 to 15). Increased humidity led to higher values of a for pure quartz gouge, but smaller a for the quartz-clay gouge. The effects of shear displacement and humidity are discussed in the context of particle characteristics and gouge fabric development. The extended rate-and state-dependent friction laws, using one state variable and the Ruina evolution law with normal stress variation, describe our observations.Components: 9324 words, 15 figures, 1 table.

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On the importance of normal vibrations in modeling of stick slip in rock sliding

Cited by 33 publications

References 36 publications

Constraining fault constitutive behavior with slip and stress heterogeneity

Constraining fault constitutive behavior with slip and stress heterogeneity

Dynamic Earthquake Ruptures in the Presence of Lithostatic Normal Stresses: Implications for Friction Models and Heat Production

Effects of normal stress perturbations on the frictional properties of simulated faults

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