Dilatant strengthening as a mechanism for slow slip events

Segall, P.; Rubin, Allan M.; Bradley, Andrew M.; Rice, James R.

doi:10.1029/2010jb007449

Cited by 371 publications

(520 citation statements)

References 72 publications

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“…However, note that many areas on natural faults should have small nucleation sizes to produce small events. Other mechanisms have been proposed to explain aseismic transients, such as inelastic dilatancy and complex dependence of friction on slip velocity [e.g., Segall and Rubin, 2007;Shibazaki and Shimamoto, 2007].…”

Section: Discussionmentioning

confidence: 99%

Three‐dimensional boundary integral modeling of spontaneous earthquake sequences and aseismic slip

2009

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[1] Fault processes involve complex patterns of seismic events and aseismic slip. This work develops a three-dimensional (3-D) methodology for simulating long-term history of spontaneous seismic and aseismic slip on a vertical planar strike-slip fault subjected to slow tectonic loading. Our approach reproduces all stages of earthquake cycles, from accelerating slip before dynamic instability, to rapid dynamic propagation of earthquake rupture, to postseismic slip, and to interseismic creep, including aseismic transients. We use the developed 3-D methodology to study interaction of fault slip with a small patch of higher normal stress over long-term slip history. For uniform initial prestress, dynamic rupture is significantly affected by the stronger patch in the first simulated event but not in subsequent ones. The change in behavior is due to redistribution of shear stress by prior slip, which demonstrates that distributions of fault strength and stress are related and illustrates the importance of simulating long slip histories even in studies of dynamic rupture. Despite no long-term effect on dynamic rupture, the small patch of higher normal stress influences nucleation processes and hence long-term slip patterns in the model. Comparison of the fully dynamic simulations and a widely used quasi-dynamic approach shows that the quasi-dynamic approach modifies long-term slip patterns in addition to resulting in much smaller slip velocities and rupture speeds during dynamic events. We show that the response of quasi-dynamic formulations with reduced radiation damping terms can be scaled to match the results of the standard quasi-dynamic formulation and hence cannot improve the comparison.Citation: Lapusta, N., and Y. Liu (2009), Three-dimensional boundary integral modeling of spontaneous earthquake sequences and aseismic slip,

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Section: Discussionmentioning

confidence: 99%

Three‐dimensional boundary integral modeling of spontaneous earthquake sequences and aseismic slip

2009

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“…The low effective normal stresses are consistent with the triggering and modulation of tremor by small dynamic stresses such as passing surface waves (Rubinstein et al, 2007) and tidal stresses (Royer et al, 2015;Rubinstein et al, 2008), as well as numerical modeling of slow slip (Liu and Rice, 2007;Rubin, 2008;Segall et al, 2010). Based on the spatial correspondence between the LVZ and the slow earthquake source region, it is tempting to conjecture that high pore-fluid pressures inferred from elevated Vp/Vs values are responsible for deep episodic slow earthquake activity.…”

Section: Accepted M Manuscriptmentioning

confidence: 99%

Teleseismic constraints on the geological environment of deep episodic slow earthquakes in subduction zone forearcs: A review

2016

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More than a decade after the discovery of deep episodic slow slip and tremor, or slow earthquakes, at subduction zones, much research has been carried out to investigate the structural and seismic properties of the environment in which they occur. Slow earthquakes generally occur on the megathrust fault some distance downdip of the great earthquake seismogenic zone in the vicinity of the mantle wedge corner, where three major structural elements are in contact: the subducting oceanic crust, the overriding forearc crust and the continental mantle. In this region, thermo-petrological models predict significant fluid production from the dehydrating oceanic crust and mantle due to prograde metamorphic reactions, and their consumption by hydrating the mantle wedge. These fluids are expected to affect the dynamic stability of the megathrust fault and enable slow slip by increasing pore-fluid pressure and/or reducing friction in fault gouges.Resolving the fine-scale structure of the deep megathrust fault and the in situ distribution of fluids where slow earthquakes occur is challenging, and most advances have been made using A C C E P T E D M A N U S C R I P T ACCEPTED MANUSCRIPTteleseismic scattering techniques (e.g., receiver functions). In this paper we review the teleseismic structure of six well-studied subduction zones (three hot, i.e., Cascadia, southwest Japan, central Mexico, and three cool, i.e., Costa Rica, Alaska, and Hikurangi) that exhibit slow earthquake processes and discuss the evidence of structural and geological controls on the slow earthquake behavior. We conclude that changes in the mechanical properties of geological materials downdip of the seismogenic zone play a dominant role in controlling slow earthquake behavior, and that near-lithostatic pore-fluid pressures near the megathrust fault may be a necessary but insufficient condition for their occurrence.

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“…This tendency of the slip law was also reported by Rubin [2008]; this tendency might be pronounced in our model since the model does not contain any regions of velocity strengthening (a/b > 1). In order to cause spontaneous slow slip events to appear in a fault with the slip law, it is necessary to have rheological frictional heterogeneities [Mitsui and Hirahara, 2008] or evolution of pore fluid pressure [Segall et al, 2010].…”

Section: In the Case Of The Slip Lawmentioning

confidence: 99%

Fault instability on a finite and planar fault related to early phase of nucleation

Mitsui¹,

Hirahara²

2011

J. Geophys. Res.

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[1] We numerically investigate the early phase of nucleation on a planar fault with the rate-and state-dependent friction law, loaded externally by steady slip, to clarify its relation to fault instability. We define R n as the invasion distance of the inward creep to characterize that phase. For a circular fault, the dependence of R n on the dimensionless parameters l b , l b−a , and l RA (all of these are proportional to the rigidity and the characteristic distance of the state evolution L and inversely proportional to the normal stress and the fault radius) can be compiled. We found that R n is proportional to l b (both aging law and slip law of the state evolution) and l b−a (aging law). In the case of the aging law only, there are two regimes (ordinary events and slow events) separated by the value of l RA . The regimes have different trend lines, although we could not measure R n for the case of l RA < 0.35 because of breaking of the mirror symmetry of instability along the loading direction. R n in the slow event regime is smaller. Moreover, we investigated the effect of fault shape and found that a model with a long radius along the mode 2 direction has similar parameter dependence to circular faults, but a model with a long radius along the mode 3 direction has different ones. Our results imply that we can qualitatively estimate the fault instability parameters from the early phase of nucleation, although further research is necessary to enable application to actual faults.Citation: Mitsui, Y., and K. Hirahara (2011), Fault instability on a finite and planar fault related to early phase of nucleation,

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Dilatant strengthening as a mechanism for slow slip events

Cited by 371 publications

References 72 publications

Three‐dimensional boundary integral modeling of spontaneous earthquake sequences and aseismic slip

Three‐dimensional boundary integral modeling of spontaneous earthquake sequences and aseismic slip

Teleseismic constraints on the geological environment of deep episodic slow earthquakes in subduction zone forearcs: A review

Fault instability on a finite and planar fault related to early phase of nucleation

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