Toward the Formulation of a Realistic Fault Governing Law in Dynamic Models of Earthquake Ruptures

Bizzarri, Andrea

doi:10.5772/7087

Cited by 3 publications

(5 citation statements)

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“…The transition between a Coulomb rheology to a viscous rheology occurs spontaneously, as discussed in section 5.3, and depends on the evolution of the temperature on the fault surface. We emphasize that the model proposed here can be generalized to other more elaborated Coulombian governing models, such as nonlinear SW equations or rate-and state-dependent friction laws (see Bizzarri [2010a] for a review). The adoption of a linear SW friction before melting makes simple the identification of the transition to viscous rheology.…”

Section: Discussionmentioning

confidence: 99%

“…[10] In the present paper we consider a more general fault structure than that adopted by BC06a and BC06b [see also Evans and Chester, 1995;Sibson, 2003;Bizzarri, 2010a]. As reported in Figure 1, a highly fractured, damage zone surrounds the slipping zone where the slip is concentrated.…”

Section: Model Of the Fault Zone And Statement Of The Problemmentioning

confidence: 99%

“…In equation (3), v denotes the magnitude of the fault slip velocity and t denotes the magnitude of the fault traction, expressed by the governing law in the unmelted regime, which can be the slip-weakening law [e.g., Ida, 1972], a rate-and state-dependent friction law [e.g., Dieterich, 1979], the law for the flash heating of microasperity contacts [Noda et al, 2009, and references therein], etc. (see Bizzarri [2010a] for a discussion). On the fault plane (i.e., in the limit z = 0), equation (3) reduces to (see also BC06a, their equation (6)):…”

Section: Temperature Evolution Before the Melting Timementioning

confidence: 99%

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Dynamic seismic ruptures on melting fault zones

Bizzarri

2011

J. Geophys. Res.

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[1] We present a physical model that describes the behavior of spontaneous earthquake ruptures dynamically propagating on a fault zone and that accounts for the presence of frictional melt produced by the sliding surfaces. First, we analytically derive the solution for the temperature evolution inside the melt layer, which generalizes previous approximations. Then we incorporate such a solution into a numerical code for the solution of the elastodynamic problem. When a melt layer is formed, the linear slip-weakening law (initially governing the fault and relying on the Coulomb friction) is no longer valid. Therefore we introduce on the fault a linearly viscous rheology, with a temperature-dependent dynamic viscosity. We explore through numerical simulations the resulting behavior of the traction evolution in the cohesive zone before and after the transition from Coulomb friction and viscous rheology. The predictions of our model are in general agreement with the data from exhumed faults. We also find that the fault, after undergoing the breakdown stress drop controlled by the slip-weakening constitutive equation, experiences a second traction drop controlled by the exponential weakening of fault resistance due to the viscous rheology. This further drop enhances the instability of the fault, increasing the rupture speeds, the peaks in fault slip velocity, and the fracture energy density.

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Section: Discussionmentioning

confidence: 99%

Section: Model Of the Fault Zone And Statement Of The Problemmentioning

confidence: 99%

Section: Temperature Evolution Before the Melting Timementioning

confidence: 99%

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Dynamic seismic ruptures on melting fault zones

Bizzarri

2011

J. Geophys. Res.

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“…Figure 2 (a)-(c) shows the static, dynamic and Coulomb stress change due to the Uttarkashi main event. The stress change for each grid is calculated using the Navier's method of stress determination (Bizzarri 2010). Blue (for negative change) and red colour (for positive change) are used to denote the variations of stress changes in a graphical manner.…”

Section: Study Of Coulomb Stress Changementioning

confidence: 99%

Himalayan hazard study on the basis of stress and strain state of 1991 Uttarkashi earthquake using Coulomb stress transfer model

Gupta

Bhowmick

Roy

2013

Geomatics, Natural Hazards and Risk

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Uttarkashi region of Himalaya was struck by a destructive earthquake (M w ¼ 6.8) on 19 October 1991 with its epicentre located at 30.78 N latitude and 78.77 E longitude.Here, we use Coulomb stress model for the study of this major event. Coulomb 3.1 application is used to generate the earthquake model and develop the stress change maps of the region. The 1991 Uttarkashi earthquake and succeeding earthquakes of M b > 3.5 are used for the study. One of the motives of this work is to correlate the main shock and the successive minor earthquakes that have occurred in the region. Further, we have studied the 1999 Chamoli earthquake using this model and attempted to relate its occurrence with the Uttarkashi earthquake based on propagation of strain energy.The study of Uttarkashi 1991 earthquake by this method supports the main shock and its controlling effect on the later earthquakes' observations in the nearby region with the view that many zones of such shock can occur in the future. This model is also used to predict the direction of propagation of strain energy, thereby locating the region that will be affected by the future shocks.

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“…In the recent literature, there is a lively debate about the most reasonable and realistic (from a physical point of view) analytical formulation of a fault governing law (Bizzarri and Cocco, 2006;Rice and Cocco, 2007) and the issue is still open (Bizzarri, 2010). The most widely adopted (see for instance Harris et al, 2009) constitutive model is the slipweakening (SW) law, which prescribes that the magnitude τ of fault traction decreases for increasing cumulative fault slip (Ida, 1972).…”

Section: Introductionmentioning

confidence: 99%

How to Promote Earthquake Ruptures: Different Nucleation Strategies in a Dynamic Model with Slip-Weakening Friction

Bizzarri¹

2010

Bulletin of the Seismological Society of America

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The introduction of the linear slip-weakening friction law permits the solution of the elastodynamic equation for a rupture that develops on a fault by removing the singularity in the components of stress tensor, thereby ensuring a finite energy flux at the crack tip. With this governing model, largely used by seismologists, it is possible to simulate a single earthquake event; but, in the absence of remote tectonic loading, it requires the introduction of an artificial procedure to initiate the rupture (i.e., to reach the failure stress point). In this article, by studying the dynamic rupture propagation and the solutions on the fault and on the free surface, I systematically compare three conceptually and algorithmically different nucleation strategies widely adopted in the literature: the imposition of an initially constant rupture speed, the introduction of a shear stress asperity, and the perturbation to the initial particle velocity field. My results show that, contrary to supershear ruptures, which tend to forget their origins, subshear ruptures are quite sensitive to the adopted nucleation procedure, which can bias the runaway rupture. I confirm that the most gradual transition from imposed nucleation and spontaneous propagation is obtained by initially forcing the rupture to expand at a properly chosen, constant speed (0.75 times the Rayleigh speed). I also numerically demonstrate that a valid alternative to this strategy is an appropriately smoothed, elliptical shear stress asperity. Moreover, I evaluate the optimal size of the nucleation patch where the procedure is applied; the simulations indicate that its size has to equal the critical distance of Day (1982) in the case of supershear ruptures and to exceed it in the case of subshear ruptures.

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Toward the Formulation of a Realistic Fault Governing Law in Dynamic Models of Earthquake Ruptures

Cited by 3 publications

References 65 publications

Dynamic seismic ruptures on melting fault zones

Dynamic seismic ruptures on melting fault zones

Himalayan hazard study on the basis of stress and strain state of 1991 Uttarkashi earthquake using Coulomb stress transfer model

How to Promote Earthquake Ruptures: Different Nucleation Strategies in a Dynamic Model with Slip-Weakening Friction

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