Earthquake Ruptures with Strongly Rate-Weakening Friction and Off-Fault Plasticity, Part 1: Planar Faults

Dunham, Eric M.; Belanger, David; Lin, Cong; Kozdon, Jeremy E.

doi:10.1785/0120100075

Cited by 166 publications

(237 citation statements)

References 101 publications

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“…More experimental support, such as that provided by Tanikawa et al (2010), is necessary to clarify this problem. Lastly, the effect of offfault plastic yielding can restrain the dynamic-weakening effect (e.g., Andrews, 2005;Dunham et al, 2011). By contrast, the effect of material contrast across the fault (e.g., Ben-Zion, 2001;Ma and Beroza, 2008) may not counteract the dynamic-weakening effect in this case, since a hanging wall in a subduction fault is considered to be more compliant than a footwall.…”

Section: Effective But Moderate Tpmentioning

confidence: 98%

A scenario for the generation process of the 2011 Tohoku earthquake based on dynamic rupture simulation: Role of stress concentration and thermal fluid pressurization

2012

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We perform dynamic rupture simulations to improve the understanding of the generation process of the 2011 Tohoku earthquake. We assume a dynamic weakening mechanism (dynamic thermal pressurization of pore fluid, hereinafter called TP) on the fault plane to represent nonlinear weakening friction, and take into account the shear stress changes before the Tohoku earthquake, due to the four M 7-class earthquakes that occurred during [2003][2004][2005][2006][2007][2008][2009][2010][2011]. To constrain the dynamic rupture simulation, the moment release rate obtained by seismic slip inversions is referred. The simulation result implies the following about the 2011 Tohoku earthquake: (1) The rupture around the hypocenter was enhanced by the stress accumulation due to the preceding M 7-class earthquakes. (2) The enhanced rupture triggered the TP mechanism in the near-trench area causing large slip, which promoted propagation of the rupture over a wide region including the source areas of the M 7-class earthquakes and surrounding conditionally-stable areas. (3) Without sufficient stress accumulation, the moment release of the Tohoku earthquake ended as an M 8-class earthquake. (4) TP in the near-trench area should be effective but moderate. The occurrence time of the next megaquake would be strongly affected by the nonlinear effects of TP and the stress conditions. Thus, our model may contradict the concept of the (quasi-)cyclic occurrence of M 9 earthquakes.

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Section: Effective But Moderate Tpmentioning

confidence: 98%

A scenario for the generation process of the 2011 Tohoku earthquake based on dynamic rupture simulation: Role of stress concentration and thermal fluid pressurization

2012

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“…The rapid rupture initiation could potentially be delayed by considering fault structures more complex than the curved, yet purely strike-slip fault geometry used in our simulation. Including small-scale geometrical roughness may additionally slow down rupture and limit the stress drop [Dunham et al, 2011b;Shi and Day, 2013;Zielke et al, 2017;Mai et al, 2017], while simultaneously increasing off-fault damage.…”

Section: Early Moment Release and Earthquake Initiationmentioning

confidence: 99%

Landers 1992 "reloaded": Integrative dynamic earthquake rupture modeling

Gabriel

Wollherr

Schliwa

et al. 2018

Preprint

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Key Points:• A new integrative physics-based simulation of the 1992 Landers earthquake reproduces a broad range of independent observation • Sustained dynamic rupture interconnecting the complex fault segments constraints pre-stress and fault strength • We discuss the interplay of rupture transfers, geometric fault complexity, initial stress, viscoelastic attenuation, and off-fault plasticity AbstractThe 1992 M w 7.3 Landers earthquake is perhaps one of the best studied seismic events. However, many aspects of the dynamics of the rupture process are still puzzling, e.g. how did rupture transfer between fault segments? We present 3D spontaneous dynamic rupture simulations of a new degree of realism, incorporating the interplay of fault geometry, topography, 3D rheology, off-fault plasticity and viscoelastic attenuation. The surprisingly unique scenario reproduces a broad range of observations, including final slip distribution, seismic moment-rate function, seismic waveform characteristics and peak ground velocities, as well as shallow slip deficits and mapped off-fault deformation patterns. Sustained dynamic rupture of all fault segments in general, and rupture transfers in particular, put strong constraints on amplitude and orientation of initial fault stresses and friction. Source dynamics include dynamic triggering over large distances and direct branching; rupture terminates spontaneously on most of the principal fault segments. We achieve good agreement between synthetic and observed waveform characteristics and associated peak ground velocities. Despite very complex rupture evolution, ground motion variability is close to what is commonly assumed in Ground Motion Prediction Equations. We examine the effects of variations in modeling parameterization, e.g. purely elastic setups or models neglecting viscoelastic attenuation, in comparison to our preferred model. Our integrative dynamic modeling approach demonstrates the potential of consistent in-scale earthquake rupture simulations for augmenting earthquake source observations and improving the understanding of earthquake source physics of complex, segmented fault systems.

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“…We use a two-dimensional plane strain model that incorporates strongly rate-weakening friction on the fault and Drucker-Prager viscoplasticity to account for inelastic deformation of the off-fault material. Detailed descriptions of friction, plasticity, and material parameters can be found in Dunham et al [2011aDunham et al [ , 2011b; the numerical method (a high-order finite difference method) is described in Dunham et al [2011a] and Kozdon et al [2011Kozdon et al [ , 2012.…”

Section: Model Descriptionmentioning

confidence: 99%

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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Earthquake Ruptures with Strongly Rate-Weakening Friction and Off-Fault Plasticity, Part 1: Planar Faults

Cited by 166 publications

References 101 publications

A scenario for the generation process of the 2011 Tohoku earthquake based on dynamic rupture simulation: Role of stress concentration and thermal fluid pressurization

A scenario for the generation process of the 2011 Tohoku earthquake based on dynamic rupture simulation: Role of stress concentration and thermal fluid pressurization

Landers 1992 "reloaded": Integrative dynamic earthquake rupture modeling

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

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