A note on fault reactivation

Sibson, Richard H.

doi:10.1016/0191-8141(85)90150-6

Cited by 689 publications

(400 citation statements)

References 13 publications

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“…The Coulomb failure criterion with Byerlee friction coefficients is the standard rule of thumb in predicting whether or not nonoptimally oriented faults can be reactivated in the present-day stress regime [e.g., Sibson, 1985;Jaeger et al, 2007]. Such methods are widely applied in the energy and mining industry and perform remarkably well in practice [e.g., Hennings et al, 2012].…”

Section: Discussionmentioning

confidence: 99%

“…Many of these faults are not optimally oriented in the present-day stress regime and have been reactivated. By assuming that faulting occurs at constant b / eff and that off-fault material strength is limited by a constant internal friction coefficient, Sibson [1985] placed bounds on the range of dip angles permitting fault reactivation. In particular, he showed there exists a lock-up angle beyond which faults become so severely misoriented that no slip can occur on them.…”

Section: Introductionmentioning

confidence: 99%

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Additional shear resistance from fault roughness and stress levels on geometrically complex faults

2013

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[1] The majority of crustal faults host earthquakes when the ratio of average background shear stress b to effective normal stress eff is b / eff 0.6. In contrast, mature plate-boundary faults like the San Andreas Fault (SAF) operate at b / eff 0.2. Dynamic weakening, the dramatic reduction in frictional resistance at coseismic slip velocities that is commonly observed in laboratory experiments, provides a leading explanation for low stress levels on mature faults. Strongly velocity-weakening friction laws permit rupture propagation on flat faults above a critical stress level pulse / eff 0.25. Provided that dynamic weakening is not restricted to mature faults, the higher stress levels on most faults are puzzling. In this work, we present a self-consistent explanation for the relatively high stress levels on immature faults that is compatible with low coseismic frictional resistance, from dynamic weakening, for all faults. We appeal to differences in structural complexity with the premise that geometric irregularities introduce resistance to slip in addition to frictional resistance. This general idea is quantified for the special case of self-similar fractal roughness of the fault surface. Natural faults have roughness characterized by amplitude-to-wavelength ratios˛between 10 -3 and 10 -2 . Through a second-order boundary perturbation analysis of quasi-static frictionless sliding across a band-limited self-similar interface in an ideally elastic solid, we demonstrate that roughness induces an additional shear resistance to slip, or roughness drag, given by drag = 8 3˛2 G * / min , for G * = G/(1 -) with shear modulus G and Poisson's ratio , slip , and minimum roughness wavelength min . The influence of roughness drag on fault mechanics is verified through an extensive set of dynamic rupture simulations of earthquakes on strongly rate-weakening fractal faults with elastic-plastic off-fault response. The simulations suggest that fault rupture, in the form of self-healing slip pulses, becomes probable above a background stress level b pulse + drag . For the smoothest faults (˛ 10 -3 ), drag is negligible compared to frictional resistance, so that b pulse 0.25 eff . However, on rougher faults (˛ 10 -2 ), roughness drag can exceed frictional resistance. We expect that drag ultimately departs from the predicted scaling when roughness-induced stress perturbations activate pervasive off-fault inelastic deformation, such that background stress saturates at a limit ( b 0.6 eff ) determined by the finite strength of the off-fault material. We speculate that this strength, and not the much smaller dynamically weakened frictional strength, determines the stress levels at which the majority of faults operate.Citation: Fang, Z., and E. M. Dunham (2013), Additional shear resistance from fault roughness and stress levels on geometrically complex faults,

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Additional shear resistance from fault roughness and stress levels on geometrically complex faults

2013

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“…Froitzheim & Eberli 1990;Lister et al 1991;Reston et al 1996;Driscoll & Karner 1998;Hodges et al 1998;Osmundsen et al 1998;Taylor et al 1999;Boncio et al 2000;Manatschal et al 2001;Canales et al 2004). However, the apparent conflict between generally accepted geological interpretations and rock mechanical and seismological considerations has yet to be resolved satisfactorily (Sibson 1985;Jackson 1987;Jackson & White 1989;Collettini & Sibson 2001;Scholz & Hanks 2004;cf. Axen 1992cf.…”

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confidence: 99%

“…Beginning in the early 1990s, we became interested in Basin and Range examples for which evidence was regarded by the structural geological community to be the most compelling for slip at dips of appreciably less than 308 -the lowest plausible frictional lock-up angle for crustally rooted normal faults in the absence of unusual materials (m , 0.6, where m is the coefficient of friction) (Sibson 1985;Collettini & Sibson 2001) -and for the very large extensional strains with which low-angle normal faults are commonly associated Levy & ChristieBlick 1989;Snow & Wernicke 2000). We reasoned that if progress was to be made in developing a better theoretical understanding, it would be useful to focus on geological examples providing the firmest constraints.…”

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confidence: 99%

Observations from the Basin and Range Province (western United States) pertinent to the interpretation of regional detachment faults

Christie‐Blick

Anders

Wills

et al. 2007

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This paper summarizes the results of completed and ongoing research in three areas of the Basin and Range Province of the western United States that casts doubt on the interpretation of specific regional detachment faults and the large extensional strains with which such faults are commonly associated. Given that these examples were influential in the development of ideas about low-angle normal faults, and particularly in making the case for frictional slip at dips of appreciably less than the 308 lock-up angle for m 0.6 (where m is the coefficient of friction), we advocate a critical re-examination of interpreted detachments elsewhere in the Basin and Range Province and in other extensional and passive margin settings.The Sevier Desert 'detachment' of west-central Utah is reinterpreted as a Palaeogene unconformity that has been traced to depth west of the northern Sevier Desert basin along an unrelated seismic reflection (most probably a splay of the Cretaceous-age Pavant thrust). The absence of evidence in well cuttings and cores for either brittle deformation (above) or ductile deformation (below) is inconsistent with the existence of a fault with as much as 40 km of displacement. The Pavant thrust and the structurally higher Canyon Range thrust are erosionally truncated at the western margin of the southern Sevier Desert basin, and are not offset by the 'detachment' in the manner assumed by those inferring large extension across the basin.The Mormon Peak detachment of SE Nevada is reinterpreted as a series of slide blocks on the basis of detachment characteristics and spatially variable kinematic indicators that are more closely aligned with the modern dip direction than the inferred regional extension direction. A particularly distinctive feature of the detachment is a basal layer of up to several tens of centimetres of polymictic conglomerate that was demonstrably involved in the deformation, with clastic dykes of the same material extending for several metres into overlying rocks in a manner remarkably similar to that observed at rapidly emplaced slide blocks. The Castle Cliff detachment in the nearby Beaver Dam Mountains of SW Utah is similarly regarded as a surficial feature, as originally interpreted, and consistent with its conspicuous absence in seismic reflection profiles from the adjacent sedimentary basin.The middle Miocene Eagle Mountain Formation of eastern California, interpreted on the basis of facies evidence and distinctive clast provenance to have been moved tectonically more than 80 km ESE from a location close to the Jurassic-age Hunter Mountain batholith of the Cottonwood Mountains, is reinterpreted as having accumulated in a fluvial-lacustrine rather than alluvial fanlacustrine setting, with no bearing on either the amount or direction of tectonic transport. The conglomeratic rocks upon which the provenance argument was based are pervasively channelized, with erosional relief of less than 1 m to as much as 15 m, fining-upwards successions at the same scale and abundant trough ...

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“…The criteria are independent of fault type. The maximum stresses available for reactivation of misoriented faults are limited by the frictional strength of the immediately adjacent wall rock (Figure 1), which must not fail in shear or tension [e.g., Sibson, 1985Sibson, , 1989. Such failure would lead to fluid leakage from the fault core into the wall rock, and the associated fluid pressure decrease is inferred to prevent fault reactivation.…”

Section: Stress States At Seismogenic Depthmentioning

confidence: 99%

Conditions for earthquake surface rupture along the San Andreas Fault System, California

Streit¹

1999

J. Geophys. Res.

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Abstract. Earthquake ruptures that nucleate along faults at depth can only propagate to the Earth's surface if the shear stresses during faulting exceed the yield strength of the uppermost crust, where fluid pressures are usually hydrostatic. Suprahydrostatic fluid pressures may be required at depth for the seismic reactivation of misoriented faults, such as the San Andreas fault system. Based on fracture criteria for the wall and fault rock, slip events that can cause ground breakage are estimated to occur at seismogenic depth along fault planes that form angles of less than 65 ø on average with the maximum principal stress direction. Such slip events require minimum shear stresses of about 30 MPa at hypocentral depth. For faults with long interseismic periods, and thus, inferred high cohesive strength, the predicted reactivation angle is < 55 ø, suggesting that several segments of the San Andreas fault system in southern California, including the San Bernardino area, parts of the Elsinore fault zone and the San Jacinto fault, provide the most probable hypocentral sites for future large earthquakes that disrupt the surface. To provide further constraints on locations for such earthquakes, we urgently need to investigate frictional properties of fault rocks and the state of stress at depth by employing laboratory experiments, focal mechanism studies, and by drilling into seismically active faults such as the San Andreas fault system.

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A note on fault reactivation

Cited by 689 publications

References 13 publications

Additional shear resistance from fault roughness and stress levels on geometrically complex faults

Additional shear resistance from fault roughness and stress levels on geometrically complex faults

Observations from the Basin and Range Province (western United States) pertinent to the interpretation of regional detachment faults

Conditions for earthquake surface rupture along the San Andreas Fault System, California

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