Frictional Sliding without Geometrical Reflection Symmetry

The onset of frictional motion at the interface between two distinct bodies in contact is characterized by the propagation of dynamic rupture fronts. We combine friction experiments and numerical simulations to study the properties of these frictional rupture fronts. We extend previous analysis of slow and sub-Rayleigh rupture fronts and show that strain fields and the evolution of real contact area in the tip vicinity of supershear ruptures are well described by analytical fracture-mechanics solutions. Fracture-mechanics theory further allows us to determine long sought-after interface properties, such as local fracture energy and frictional peak strength. Both properties are observed to be roughly independent of rupture speed and mode of propagation. However, our study also reveals discrepancies between measurements and analytical solutions that appear as the rupture speed approaches the longitudinal wave speed. Further comparison with dynamic simulations illustrates that, in the supershear propagation regime, transient and geometrical (finite sample thickness) effects cause smaller near-tip strain amplitudes than expected from the fracturemechanics theory. By showing good quantitative agreement between experiments, simulations and theory over the entire range of possible rupture speeds, we demonstrate that frictional rupture fronts are classic dynamic cracks despite residual friction.

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“…Calibration of these effects is shortly described in Ref. [35] and further details are provided in Appendix A.…”

Section: Experimental Systemmentioning

confidence: 99%

Dynamic fields at the tip of sub-Rayleigh and supershear frictional rupture fronts

Svetlizky

Albertini

Cohen

et al. 2020

Journal of the Mechanics and Physics of Solids

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“…An important outcome of this study is that the symmetry breaking leads to a dependence of the rupture dynamics on the absolute level of friction: A higher level of friction induces a larger amplitude of the slip‐induced normal traction perturbations, which in turn favor the updip rupture propagation increasing the inertia effect and the slip rate enhancement. This result is supported by a linear stability analysis (Aldam et al, ) showing frictional dependence of the sliding for a system that lacks reflection symmetry across the interface.…”

Section: Discussionmentioning

confidence: 65%

Wave Interaction of Reverse‐Fault Rupture With Free Surface: Numerical Analysis of the Dynamic Effects and Fault Opening Induced by Symmetry Breaking

et al. 2019

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Several great earthquakes occur on thrust faults along both subduction and continental collision zones. These events often feature a large shallow slip patch, an asymmetric pattern for the ground motion, and the static deformation between the hanging wall and footwall of the fault. From a mechanical point of view, this asymmetry can be partially explained taking into account the interaction between the fault and the seismic radiation emitted during rupture propagation and stored in the hanging wall in the vicinity of the free surface. We numerically investigate the rupture dynamics along a thrust dipping fault impacting onto the free surface at a dip angle of δ = 20°, in a 2‐D elastic model. We show how the wave interaction of the rupture with the free surface leads to a breaking of the reflection symmetry. Compared to a rupture propagating in an infinite medium, this interaction enhances the slip rate in the updip direction as an effect of the coupling between slip and normal traction around the crack front. The breaking of symmetry leads to sizeable acceleration of the rupture toward asymptotic speed with inertia acquisition, and dependence of the rupture dynamics on the level of friction along the interface might produce an interface opening over a finite length in the vicinity of the surface. We finally explore how the wave interaction drives amplification and asymmetry of the shallow slip and the vertical displacement at the surface. The described effects should be considered in various numerical approaches and in interpretation of geophysical observations.

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“…Some of the analyses performed in this study can be extended to other configurations producing dynamic changes in normal stress along a frictional interface. Examples include contrast in poroelastic properties across faults (Dunham & Rice, ) and asymmetric geometrical properties of the solids across faults (Aldam et al, ), where the latter are directly relevant to geometric variations and free surface effects on dipping faults (Gabuchian et al, ; Oglesby, ). In this context, it is interesting to note that several of these effects, and the elastodynamic bimaterial effect analyzed in this study, can coexist at the shallow portions of subduction zones.…”

Section: Summary and Discussionmentioning

confidence: 99%

Nonmonotonicity of the Frictional Bimaterial Effect

Aldam

Brener

et al. 2017

JGR Solid Earth

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Sliding along frictional interfaces separating dissimilar elastic materials is qualitatively different from sliding along interfaces separating identical materials due to the existence of an elastodynamic coupling between interfacial slip and normal stress perturbations in the former case. This bimaterial coupling has important implications for the dynamics of frictional interfaces, including their stability and rupture propagation along them. We show that while this bimaterial coupling is a monotonically increasing function of the bimaterial contrast, when it is coupled to interfacial shear stress perturbations through a friction law, various physical quantities exhibit a nonmonotonic dependence on the bimaterial contrast. In particular, we show that for a regularized Coulomb friction, the maximal growth rate of unstable interfacial perturbations of homogeneous sliding is a nonmonotonic function of the bimaterial contrast and provides analytic insight into the origin of this nonmonotonicity. We further show that for velocity‐strengthening rate‐and‐state friction, the maximal growth rate of unstable interfacial perturbations of homogeneous sliding is also a nonmonotonic function of the bimaterial contrast. Results from simulations of dynamic rupture along a bimaterial interface with slip‐weakening friction provide evidence that the theoretically predicted nonmonotonicity persists in nonsteady, transient frictional dynamics.

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Frictional Sliding without Geometrical Reflection Symmetry

Cited by 21 publications

References 78 publications

Dynamic fields at the tip of sub-Rayleigh and supershear frictional rupture fronts

Dynamic fields at the tip of sub-Rayleigh and supershear frictional rupture fronts

Wave Interaction of Reverse‐Fault Rupture With Free Surface: Numerical Analysis of the Dynamic Effects and Fault Opening Induced by Symmetry Breaking

Nonmonotonicity of the Frictional Bimaterial Effect

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