Simulation of slip transients and earthquakes in finite thickness shear zones with a plastic formulation

Tong, X.; Lavier, L. L.

doi:10.1038/s41467-018-06390-z

Cited by 24 publications

(32 citation statements)

References 54 publications

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“…These characteristics are similar in all the cases displaying mixed‐mode slip behaviors (Figure 4). These events follow the scaling relationships described in Tong and Lavier (2018). The durations and moments of modeled slow events plot around the linear relationship observed in natural SSEs (Ide et al., 2007; Peng & Gomberg, 2010) while those of the simulated earthquakes plot near the cubic moment‐duration scaling.…”

Section: Resultssupporting

confidence: 76%

“…A fault zone of finite thickness is used to simulate the formation of shear zones and fractures on which creep and slip events occur following the numerical approach of Tong and Lavier (2018). A key aspect of this numerical method is that it simulates long‐term tectonic processes and earthquakes by using an adaptive time stepping algorithm (Lapusta & Liu, 2009; Lapusta et al., 2000; Tong & Lavier, 2018). The quasistatic solution to the momentum equation is reached by using dynamic relaxation that damps the inertial components of motion (Choi et al., 2013; Cundall, 1989; Tan et al., 2012; Tong & Lavier, 2018).…”

Section: Methodsmentioning

confidence: 99%

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The Mechanics of Creep, Slow Slip Events, and Earthquakes in Mixed Brittle‐Ductile Fault Zones

2021

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Geological observations show that fault zone composition varies and often accommodates a mixture of brittle and ductile deformation. There is growing evidence that the nature of this mixture may play an important role in determining whether the fault creeps steadily or slides in slow slip events (SSEs) and/or fast earthquakes. Using numerical experiments of slip events in a fault zone of finite thickness, we explore how the ratio of brittle to ductile material and the absolute friction change resulting from a variation in slip velocity, |b−a|, affect energy partitioning and slip behavior in brittle‐ductile mixtures. We treat brittle material as Mohr‐Coulomb elastoplastic and ductile material as Maxwell viscoelastic. We simulate velocity‐weakening (a−b<0) behavior in the brittle part of the mixture and velocity‐strengthening (a−b≥0) behavior in the ductile part using a rate‐and‐state formulation dependent on plastic strain accumulation. We show that: (1) mixtures can exhibit multiple slip behaviors including earthquakes and slow slip, (2) highly brittle mixtures do not tend to generate SSEs while weakly brittle mixtures can generate slow slip over a wider range of compositions, (3) structural features formed during simulated creep, SSEs, and earthquakes share notable similarities with structures observed in natural fault zones. We find that slip‐synchronous strengthening in the ductile portion of the mixture controls whether a rupture propagates as SSEs of yearlong durations. Shorter duration SSEs occur when the length of the plastic shear segments formed during slip is similar to the characteristic weakening distance for an earthquake.

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Section: Resultssupporting

confidence: 76%

Section: Methodsmentioning

confidence: 99%

The Mechanics of Creep, Slow Slip Events, and Earthquakes in Mixed Brittle‐Ductile Fault Zones

2021

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“…Several variants of rate‐and‐state fault models can significantly extend the range of parameters suitable for SSEs, including changes from velocity‐weakening to velocity‐strengthening friction with increasing slip rates (Leeman et al, 2016; Shibazaki & Shimamoto, 2007), geometric complexities and roughness (Li & Liu, 2016; Ozawa et al, 2019; Romanet et al, 2018), and decreases in pore fluid pressure due to shear‐induced dilatancy (Marone et al, 1990; Segall & Rice, 1995; Segall et al, 2010). SSEs can also be obtained in models of rate‐and‐state faults with velocity‐strengthening friction and additional destabilizing effects, for example, poroelastic (Heimisson et al, 2019), and in models with viscoplastic bulk effects (Tong & Lavier, 2018). Here, we show that a model of SSEs on a rate‐and‐state fault with a depth‐bounded velocity‐weakening region (Figure 1e) can explain the cubic moment‐duration scaling of slow slip observed in Cascadia.…”

Section: Introductionmentioning

confidence: 99%

Unraveling Scaling Properties of Slow‐Slip Events

Zilio

Lapusta

Avouac

2020

Geophysical Research Letters

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A major debate in geophysics is whether earthquakes and slow-slip events (SSEs) arise from similar failure mechanisms. Recent observations from different subduction zones suggest that SSEs follow the same moment-duration scaling as earthquakes, unlike qualitatively different scaling proposed by earlier studies. Here, we examine the scaling properties using dynamic simulations of frictional sliding. The resulting sequences of SSEs match observations from the Cascadia subduction zone, including the earthquake-like cubic moment-duration scaling. In contrast to conventional and widely used assumptions of magnitude-invariant rupture velocities and stress drops, both simulated and natural SSEs have rupture velocities and stress drops that increase with event magnitudes. These findings support the same frictional origin for both earthquakes and SSEs while suggesting a new explanation for the observed SSEs scaling.Plain Language Summary Tectonic faults produce a wide spectrum of slip modes, ranging from fast earthquakes to slow-slip events. Whether slow-slip events and regular earthquakes result from a similar physics is debated. Here we present numerical simulations to show that slow-slip events can result from frictional sliding like seismic slip, with an additional mechanism that prevents acceleration to fast slip due to the presence of fluids. The model succeeds in reproducing a realistic sequence of slow-slip events and provides an excellent match to the observations from the Cascadia subduction zone, including the observation that the moment, which quantifies the energy released by fault slip, is proportional to the cube of the duration. Importantly, our study demonstrates that this scaling arises for different reasons from the traditional explanation proposed for regular earthquakes.

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“…The brittle/ductile transition, which marks the downdip limit of the SZ, is also a key feature notably controlling the seismicity and surface deformation (e.g., Hyndman et al., 1997). Several studies especially show that transient behavior may also be related to the interaction of unstable brittle and stable ductile behavior in mélanges in the transitions zones of the megathrust fault zone (Fagereng & Sibson, 2010; Hayman & Lavier, 2014; Saffer & Wallace, 2015; Tong & Lavier, 2018).…”

Section: Introductionmentioning

confidence: 99%

Validation of a Multilayered Analog Model Integrating Crust‐Mantle Visco‐Elastic Coupling to Investigate Subduction Megathrust Earthquake Cycle

Caniven

Dominguez

2021

JGR Solid Earth

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We have developed a scaled analog model of a subduction zone simulating seismic cycle deformation phases. Its rheology is based on multilayered visco‐elasto‐plastic materials to account for the mechanical behavior of a continental lithospheric plate overriding a subducting oceanic plate. The seismogenic zone displays unstable slip behavior, extending at depth into a weak interface with stable slip properties. The model succeeds in reproducing interseismic phases interrupted by coseismic ruptures and followed by after‐slip. The experimental data catalog shows a broad variability of slip events from aseismic slow slips to fast dynamic lab quakes. Results also show the occurrence of both isolated and precursory slow‐slip events arising before the mainshocks. Given the absence of fluids in the model, the broad variability in slip event velocity can be attributed to fault roughness complexity. The model rheology induces also a key visco‐elastic coupling between the elastic overriding plate and the mantle wedge allowing, for the first time, to reproduce experimentally a realistic postseismic visco‐elastic relaxation phase. Preliminary results reveal that the tectonic loading rate modulates this visco‐elastic coupling. A low loading rate weakens it, which increase the amount of storable interseismic elastic deformation, and favors the occurrence of large megathrust events. A high loading rate strengthens it, which minimize the accumulation of interseismic elastic deformation, the slip‐event sizes, and promote aseismic creep. This new scaled‐analog subduction model is a complementary tool to investigate earthquake mechanics and improve the interpretation of geodetic and seismological records.

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Simulation of slip transients and earthquakes in finite thickness shear zones with a plastic formulation

Cited by 24 publications

References 54 publications

The Mechanics of Creep, Slow Slip Events, and Earthquakes in Mixed Brittle‐Ductile Fault Zones

The Mechanics of Creep, Slow Slip Events, and Earthquakes in Mixed Brittle‐Ductile Fault Zones

Unraveling Scaling Properties of Slow‐Slip Events

Validation of a Multilayered Analog Model Integrating Crust‐Mantle Visco‐Elastic Coupling to Investigate Subduction Megathrust Earthquake Cycle

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