The work budget of rough faults

Newman, Patrick; Griffith, W. A.

doi:10.1016/j.tecto.2014.08.007

Cited by 18 publications

(17 citation statements)

References 79 publications

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“…9). Following these results and previous theoretical analysis (Newman & Griffith., 2014) we speculate that the energy dissipation during natural slip is affected both by the level of normal stress and by the initial fault surface roughness. Further experimental and theoretical research focused on the transient wear stage is necessary for better simulating dissipation and partitioning of energy during earthquake.…”

Section: Applications For Natural Faultingsupporting

confidence: 76%

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Geometrical evolution of interlocked rough slip surfaces: The role of normal stress

Badt

Hatzor

Toussaint

et al. 2016

Earth and Planetary Science Letters

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International audienceWe study the evolution of slip surface topography using direct shear tests of perfectly mating surfaces. The tests are performed under imposed constant normal stress and constant slip rate conditions, to a sliding distance comparable to the roughness scale of the studied surfaces. Prismatic limestone blocks are fractured in tension using four-point bending and the generated surface topographies are measured using a laser profilometer. The initially rough fracture interfaces are tested in direct shear while ensuring a perfectly mating configuration at the beginning of each test. The predetermined sliding distance in all tests is 10 mm and the sliding velocity is 0.05mm/s. A constant normal stress is maintained throughout the tests using closed loop servo control. The range of normal stresses applied is between 2MPa and 15MPa. After shearing, the surface topographies are re-scanned and the geometrical evolution is analyzed. We find that surface roughness increases with increasing normal stress: under normal stresses below 5MPa the surfaces become smoother compared to the original geometry, whereas under normal stresses between 7.5 MPa and 15 MPa the surfaces clearly become rougher following shear. Statistical spectral analyses of the roughness profiles indicate that roughness increases with length-scale. Power spectral density values parallel to the slip orientation are fitted by power-law with typical power value of 2.6, corresponding to a Hurst exponent of 0.8, assuming self-affine roughness. This power value is consistent for the post-sheared surfaces and is obtained even when the original surface roughness does not follow initially a power-law form. The value of the scaling-law prefactor however increases with increasing normal stress. We find that the deformation associated with shearing initially rough interlocked surfaces extends beyond the immediate tested surface, further into the intact rock material. The intensity of the damage and its spatial distribution clearly increase with increasing normal stress. Wear loss is measured by subtracting the post-shear surface from the pre-shear surface matrices using known reference points. Our measurements indicate that wear loss and roughness evolution are both positively correlated with the mechanical shear work applied during the experiments. We argue, therefore, that normal stress plays a significant role in the evolution of interlocked surfaces, such as geological faults, and strongly affects the energy partitioning during slip

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Section: Applications For Natural Faultingsupporting

confidence: 76%

“…The prefactor k is therefore the parameter that chiefly varies during our shear experiments. Interestingly, computer simulations demonstrated that the prefactor of the self-affine surface roughness is the main component of roughness that affects energy dissipation during faulting (Newman & Griffith, 2014).…”

Section: Roughness Evolutionmentioning

confidence: 99%

Geometrical evolution of interlocked rough slip surfaces: The role of normal stress

Badt

Hatzor

Toussaint

et al. 2016

Earth and Planetary Science Letters

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“…And if melt welding is indeed widespread in the seismogenic zone, so too may be the process of slip delocalization. Increasing fault smoothness with fault maturity has become the accepted paradigm consistent with expectations from field observations and fault mechanics theory (Wesnousky, 1988;Chester and Chester, 1998;Brodsky et al, 2011;Newman and Griffith, 2014), yet the possibility that even mature faults may be geometrically complex at seismogenic depths has major implications for the mechanics of earthquakes and faulting. Strength heterogeneity plays a role in earthquake nucleation, propagation, and cessation, as well as off-fault deformation.…”

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confidence: 73%

RESEARCH FOCUS: How Dynamic Weakening Makes Faults Stronger: The Role Of Melting In Post-Seismic Healing

Griffith

2016

Geology

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“…We argue that fault segmentation significantly contributes to the nonplanarity of fault surfaces because, whatever their length, fault segments are separated across strike or connected through fault bends. Although continued slip tends to smooth off the smallest step overs and bends, especially along strike‐slip faults [e.g., Nur , ; Stirling et al ., ; Choy and Kirby , ; Newman and Ashley Griffith , ], some remain on the fault plane even after segments have coalesced [ Klinger , ; Candela et al ., ]. We suggest that these small‐scale nonplanar features form small “contact zones” or “protrusions” on the fault plane and hence produce roughness (Figure ).…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, the most mature seismic asperities, which host fewer contacts and are smoother, have a smaller fracture energy than the rest of the fault (less contact zones needing to be broken) [e.g., Tinti et al ., ; Ben‐David et al ., ]. They are thus zones that are most prone to be broken efficiently [e.g., Cooke and Murphy , ; Tinti et al ., ; Fang and Dunham , ; Newman and Ashley Griffith , ].…”

Section: Discussionmentioning

confidence: 99%

Location of largest earthquake slip and fast rupture controlled by along‐strike change in fault structural maturity due to fault growth

et al. 2016

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Earthquake slip distributions are asymmetric along strike, but the reasons for the asymmetry are unknown. We address this question by establishing empirical relations between earthquake slip profiles and fault properties. We analyze the slip distributions of 27 large continental earthquakes in the context of available information on their causative faults, in particular on the directions of their long‐term lengthening. We find that the largest slips during each earthquake systematically occurred on that half of the ruptured fault sections most distant from the long‐term fault propagating tips, i.e., on the most mature half of the broken fault sections. Meanwhile, slip decreased linearly over most of the rupture length in the direction of long‐term fault propagation, i.e., of decreasing structural maturity along strike. We suggest that this earthquake slip asymmetry is governed by along‐strike changes in fault properties, including fault zone compliance and fault strength, induced by the evolution of off‐fault damage, fault segmentation, and fault planarity with increasing structural maturity. We also find higher rupture speeds in more mature rupture sections, consistent with predicted effects of low‐velocity damage zones on rupture dynamics. Since the direction(s) of long‐term fault propagation can be determined from geological evidence, it might be possible to anticipate in which direction earthquake slip, once nucleated, may increase, accelerate, and possibly lead to a large earthquake. Our results could thus contribute to earthquake hazard assessment and Earthquake Early Warning.

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The work budget of rough faults

Cited by 18 publications

References 79 publications

Geometrical evolution of interlocked rough slip surfaces: The role of normal stress

Geometrical evolution of interlocked rough slip surfaces: The role of normal stress

RESEARCH FOCUS: How Dynamic Weakening Makes Faults Stronger: The Role Of Melting In Post-Seismic Healing

Location of largest earthquake slip and fast rupture controlled by along‐strike change in fault structural maturity due to fault growth

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