Segmentation of Shallow Slow Slip Events at the Hikurangi Subduction Zone Explained by Along‐Strike Changes in Fault Geometry and Plate Convergence Rates

Perez-Silva, Andrea; Kaneko, Yoshihiro; Savage, Martha K.; Wallace, Laura; Li, Duo; Williams, C. A.

doi:10.1029/2021jb022913

Cited by 8 publications

(4 citation statements)

References 123 publications

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“…To save computational costs we set the background normal stress (σ) to 3 MPa, which is below the estimated range (10-30 MPa) along the shallow Hikurangi margin (Arnulf et al, 2021). We could scale up σ by reducing the constitutive parameters a and b so that aσ and bσ remain constant, and obtain the same results, as expected from Equations 1 and 2 (e.g., Perez-Silva et al, 2022).…”

Section: Fault Model Parametersmentioning

confidence: 65%

Characteristics of slow slip events explained by rate-strengthening faults subject to periodic pore fluid pressure changes

Perez-Silva

Kaneko

Savage

et al. 2023

Preprint

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Geophysical observations indicate that temporal pore fluid pressure changes correlate with slow slip events (SSEs) occurring along the shallow portion of the Hikurangi margin and in different subduction zones. These fluctuations in pore fluid pressure are attributed to fluid migration before and during SSEs, which may modulate SSE occurrence. To examine the effect of pore fluid pressure changes on SSE generation, we develop numerical models in which periodic pore-pressure perturbations are applied to a stably sliding, rate-strengthening fault. By varying the physical characteristics of the pore-pressure perturbations (amplitude, characteristic length and period), we find models that reproduce shallow Hikurangi SSE properties (duration, magnitude, slip, recurrence) and SSE moments and durations from different subduction zones. The stress drops of modeled SSEs range from ~20-120 kPa while the amplitudes of pore-pressure perturbations is several MPa, broadly consistent with those inferred from observations. Our results indicate that large permeability values of 10 to 10 m are needed to reproduce the observed SSE properties. Such high values could be due to transient and localized increases in fault zone permeability in the shear zone where SSEs occur. Our results suggest that SSEs may arise on faults in rate-strengthening frictional conditions subject to pore-pressure perturbations.

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Section: Fault Model Parametersmentioning

confidence: 65%

Characteristics of slow slip events explained by rate-strengthening faults subject to periodic pore fluid pressure changes

Perez-Silva

Kaneko

Savage

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

“…To save computational costs, we set σ = 3 MPa, which is below the estimated range (10-30 MPa) along the shallow Hikurangi margin (Arnulf et al, 2021). We could scale up σ by reducing the constitutive parameters a and b so that aσ and bσ remain constant, and obtain the same results, as expected from Equations 1 and 2 (e.g., Perez-Silva et al, 2022). 10, see Table 4.…”

Section: Fault Model Parametersmentioning

confidence: 99%

“…Within the rate‐and‐state friction (RSF) framework (Dieterich, 1979), SSEs commonly require rate‐weakening friction to nucleate, while different mechanisms (e.g., transition to rate‐strengthening friction at higher slip speeds, Shibazaki, 2003; dilatancy strengthening, Segall et al., 2010; transitional friction behavior, Liu & Rice, 2007) have been proposed to stabilize the growing unstable slip. These models, although successful in reproducing SSE characteristics (e.g., Dal Zilio et al., 2020; Li & Liu, 2016; Liu & Rice, 2009; Matsuzawa et al., 2013; Perez‐Silva et al., 2021, 2022; Shibazaki et al., 2012, 2019), do not account for the temporal variation in pore pressure nor the widespread occurrence of rate‐strengthening materials in slow slip regions (e.g., Bürgmann, 2018; Ikari et al., 2013; Saffer & Wallace, 2015). An alternative modeling approach, proposed by Perfettini and Ampuero (2008), suggests that transient slip is induced in rate‐strengthening conditions by external stress perturbations.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of Slow Slip Events Explained by Rate‐Strengthening Faults Subject to Periodic Pore Fluid Pressure Changes

et al. 2023

Self Cite

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Geophysical observations suggest that temporal changes in pore fluid pressure correlate with slow slip events (SSEs) at some subduction zones, including the Hikurangi and Cascadia subduction zones. These fluctuations in pore fluid pressure are attributed to fluid migration before and during SSEs, which may modulate SSE occurrence. To examine the effect of pore fluid pressure changes on SSE generation, we develop numerical models in which periodic pore‐pressure perturbations are applied to a stably sliding, rate‐strengthening fault. By varying the physical characteristics of the pore‐pressure perturbations (amplitude, characteristic length and period), we find models that reproduce shallow Hikurangi SSE properties (duration, magnitude, slip, recurrence) and SSE moments and durations from different subduction zones. The stress drops of modeled SSEs range from ∼20–120 kPa while the amplitudes of pore‐pressure perturbations are several MPa, broadly consistent with those inferred from observations. Our results indicate that large permeability values of ∼10−14 to 10−10 m2 are needed to reproduce the observed SSE properties. Such high values could be due to transient and localized increases in fault zone permeability in the shear zone where SSEs occur. Our results suggest that SSEs may arise on faults in rate‐strengthening frictional conditions subject to pore‐pressure perturbations.

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“…Various analytical solutions for displacement and stress caused by surface elements are readily available to represent a displacement discontinuity embedded within an elastic half-space [Comninou and Dundurs, 1975;Okada, 1992;Meade, 2007;Gimbutas et al, 2012;Nikkhoo and Walter, 2015]. A combination of rectangle and triangle surface elements can be used to shape realistic, non-planar fault geometries [e.g., Hori et al, 2004;Qiu et al, 2016;Li and Liu, 2017;Shibazaki et al, 2019;Perez-Silva et al, 2022]. The use of analytic solutions ensures high accuracy in simulating surface displacements by resolving the free surface exactly [Qiu et al, 2016;Wang and Barbot, 2020;Sathiakumar and Barbot, 2021].…”

Section: Plain Language Summarymentioning

confidence: 99%

Numerical simulations of seismic cycles in a viscoelastic half-space with the integral method

Barbot

2023

Preprint

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Numerical simulations of seismic cycles with rate-, state-, and temperature-dependent friction explain the various modes of seismic and aseismic ruptures in the brittle section of the lithosphere. However, the effects of viscoelastic flow in the ductile layers remain challenging to incorporate due to the wide range of length scales involved, from extremely localized within fault zones to widely distributed in the lower crust and asthenosphere. Here, we describe simulations of seismic cycles in a viscoelastic half-space using the integral method that combines discrete surface and volume elements to capture the coupling between brittle and ductile deformation. Viscoelastic flow is captured by cuboidal and tetrahedral volume elements within rectilinear and curvilinear meshes, respectively. The model resolves all phases of the seismic cycle under the radiation-damping approximation, including the nucleation and propagation of earthquake ruptures, but also the viscoelastic relaxation that follows in the ductile layers. We illustrate the approach in three dimensions with numerical simulations of seismic cycles on finite strike-slip and thrust faults overlying a viscoelastic lower crust with linear and nonlinear rheology. In two-dimensional models of subduction zones with the in-plane strain approximation, the ductile regions are meshed with triangle volume elements. The use of Green’s functions only requires the discretization of the actively deforming region, resulting in a relatively small mesh. We provide open-source software implementing the method with parallel computing in a distributed architecture. The approach allows increasingly realistic representations of the lithosphere-asthenosphere system with nonlinear constitutive laws in structurally complex tectonic settings.

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Segmentation of Shallow Slow Slip Events at the Hikurangi Subduction Zone Explained by Along‐Strike Changes in Fault Geometry and Plate Convergence Rates

Cited by 8 publications

References 123 publications

Characteristics of slow slip events explained by rate-strengthening faults subject to periodic pore fluid pressure changes

Characteristics of slow slip events explained by rate-strengthening faults subject to periodic pore fluid pressure changes

Characteristics of Slow Slip Events Explained by Rate‐Strengthening Faults Subject to Periodic Pore Fluid Pressure Changes

Numerical simulations of seismic cycles in a viscoelastic half-space with the integral method

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