Postseismic quasi‐static fault slip due to pore pressure change on a bimaterial interface

Yamashita, Teruo

doi:10.1029/2006jb004667

Cited by 10 publications

(36 citation statements)

References 41 publications

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“…When the two mechanisms produce competing changes, the bimaterial effects associated with the large‐scale elastic contrast are likely to be larger for rupture velocities near the generalized Rayleigh wave speed. Yamashita (2007) found with quasi‐static calculations that a contrast of elastic and diffusivity properties across a fault lead to strongly asymmetric distribution of afterslip. It would be interesting to examine the interaction between large‐scale bimaterial contrast and small‐scale fluid‐related effects in simulations that account also for off‐fault damage, which is expected to modify considerably the permeability and diffusivity properties.…”

Section: Discussionmentioning

confidence: 88%

Cracks, pulses and macroscopic asymmetry of dynamic rupture on a bimaterial interface with velocity-weakening friction

Ampuero¹,

Ben‐Zion

2008

Geophysical Journal International

269

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SUMMARY We study in‐plane ruptures on a bimaterial fault governed by a velocity‐weakening friction with a regularized normal stress response. Numerical simulations and analytical estimates provide characterization of the ranges of velocity‐weakening scales, nucleation lengths and background stresses for which ruptures behave as cracks or pulses, decaying or sustained, bilateral or unilateral. With strongly velocity‐weakening friction, ruptures occur under a wide range of conditions as large‐scale pulses with a preferred propagation direction, that of slip of the more compliant material. Such ruptures have macroscopic asymmetry manifested by significantly larger seismic potency and propagation distance in the preferred direction, and clearly quantified by the directivity ratio derived from the second order moments of the spatio‐temporal distribution of slip rate. The macroscopic rupture asymmetry of the large‐scale pulses stems from the difference in the criticality conditions for self‐sustained propagation in each rupture direction, induced by the asymmetric normal stress changes operating in bimaterial interfaces. In contrast, crack‐like ruptures show macroscopic asymmetry under restrictive conditions. The discussed mechanism is robust with respect to regularization parameters, ranges of stress heterogeneities and a proxy for off‐fault yielding and should operate similarly for crustal‐scale rupture pulses even in the absence of velocity‐weakening. Small‐scale pulses, driven by the bimaterial normal stress reduction at the scale of the process zone, can detach from the rupture front of the large‐scale pulses that propagate in the preferred direction. However, their occurrence depends on the relaxation scale in the regularization of the normal stress response and their development can be hindered by off‐fault yielding.

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Section: Discussionmentioning

confidence: 88%

Cracks, pulses and macroscopic asymmetry of dynamic rupture on a bimaterial interface with velocity-weakening friction

Ampuero¹,

Ben‐Zion

2008

Geophysical Journal International

269

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“…Detailed parameter space studies indicate that ruptures on a bimaterial interface tend to evolve during propagation from initial symmetric cracks with relatively low mechanical efficiency to slip pulses with preferred propagation direction and high mechanical efficiency [e.g., Shi and Ben‐Zion , 2006; Brietzke et al , 2007; Dalguer and Day , 2007; Ampuero and Ben‐Zion , 2008; G. B. Brietzke et al, Importance of bimaterial interfaces for earthquake dynamics and strong ground motion, submitted to Geophysical Journal International , 2008]. Local permeability contrast across the fault can also produce asymmetric rupture as well as asymmetry of aseismic slip [ Rudnicki and Rice , 2006; Yamashita , 2007]. The progressive development of bimaterial interfaces in fault zone structures is expected to change over geological time the mode of earthquake ruptures on the fault, the energy partition during the faulting process, the ability of the fault to localize future earthquake ruptures, and a variety of related dynamic and evolutionary phenomena [ Ben‐Zion and Andrews , 1998; Ben‐Zion , 2001].…”

Section: Scale Invariance Versus Characteristic Scalesmentioning

confidence: 99%

Collective behavior of earthquakes and faults: Continuum‐discrete transitions, progressive evolutionary changes, and different dynamic regimes

Ben‐Zion¹

2008

Reviews of Geophysics

430

353

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[1] Crustal deformation patterns are affected by multiscale granulation and healing processes associated with phase transitions between continuum and discrete states of rocks. The ongoing continuum-discrete transitions are accompanied by progressive evolution of disordered fault networks to dominant localized fault zones, development of bimaterial interfaces, and increasing dynamic weakening of fault surfaces. Results on individual fault zones point to three general dynamic regimes. The first is associated with broad range of heterogeneities, little dynamic weakening, power law frequency-size statistics, temporal clustering of intermediate and large events, and accelerated seismic release before large earthquakes. The second is associated with relatively uniform localized structures, significant dynamic weakening, characteristic earthquake statistics, and quasi-periodic temporal occurrence of large events without precursory accelerated release. For a range of conditions, the fault zone response can switch back and forth between the foregoing two dynamic regimes. Higher temperature, fluid content, and thickness of sedimentary cover reduce the seismic coupling in a region and change the properties of local earthquake sequences. Brittle regions with high seismic coupling have few foreshocks and long-duration aftershock sequences with high event productivity, whereas more viscous regions with low seismic coupling have increased foreshocks activity and low-productivity aftershock sequences or swarms. The results provide criteria for organizing data in classes associated with different evolutionary stages and different regional conditions. An ability to recognize the dynamic regime of a given fault zone or a region can increase the information content of the data and lead to improved strategies for seismic hazard assessment.

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“…In contrast to his treatment, our concern here is about the effect of contrast in the hydraulic diffusivity on the generation of afterslip. Hence, our present article and the paper of Yamashita [2007] (hereinafter referred to as Paper I) form a complementary pair.…”

Section: Introductionmentioning

confidence: 97%

“… Yamashita [2007] theoretically and numerically studied the generation mechanism of afterslip taking account of spatiotemporal change of pore fluid pressure and bimaterial fault structure. He showed that quasi‐static fault tip extension is triggered by the sudden introduction of fault slip on the assumption of a fault on an interface that separates two poroelastic media with different values of drained and undrained Poisson's ratios and the Biot‐Willis coefficient.…”

Section: Introductionmentioning

confidence: 99%

Quasi‐static fault slip on an interface between poroelastic media with different hydraulic diffusivity: A generation mechanism of afterslip

Yamashita

Suzuki

2009

J. Geophys. Res.

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[1] We theoretically study the generation mechanism of afterslip, assuming a two-dimensional in-plane fault on a bimaterial interface that separates poroelastic half-spaces with different hydraulic diffusivities; the deformation is assumed to be quasi-static. Our study shows that the coseismic faulting triggers quasi-static fault tip growth effectively because of positive feedback between the evolving fault slip and fluid pressure buildup. A similar study was made by Yamashita (2007), but he assumed the difference to be only in the Biot-Willis coefficient and undrained and drained Poisson's ratios. A comparison with the model of Yamashita (2007) shows that the diffusivity contrast is much more effective for the generation of afterslip. We also find that the fault tip is likely to extend unilaterally in the direction of slip in the medium of higher diffusivity; the duration of fault growth is longer for a larger diffusivity contrast. We find a scaling relationship in which the moment released by the quasi-static fault extension is approximated well by a linear function of the duration of fault growth. This is largely different from the expectations from a 2-D classical dynamic fault model; the moment is proportional to the square of duration of fault growth if the classical fault model is assumed.Citation: Yamashita, T., and T. Suzuki (2009), Quasi-static fault slip on an interface between poroelastic media with different hydraulic diffusivity: A generation mechanism of afterslip,

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Postseismic quasi‐static fault slip due to pore pressure change on a bimaterial interface

Cited by 10 publications

References 41 publications

Cracks, pulses and macroscopic asymmetry of dynamic rupture on a bimaterial interface with velocity-weakening friction

Cracks, pulses and macroscopic asymmetry of dynamic rupture on a bimaterial interface with velocity-weakening friction

Collective behavior of earthquakes and faults: Continuum‐discrete transitions, progressive evolutionary changes, and different dynamic regimes

Quasi‐static fault slip on an interface between poroelastic media with different hydraulic diffusivity: A generation mechanism of afterslip

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