70 research outputs found
Linear elastic fracture mechanics predicts the propagation distance of frictional slip
When a frictional interface is subject to a localized shear load, it is often
(experimentally) observed that local slip events initiate at the stress
concentration and propagate over parts of the interface by arresting naturally
before reaching the edge. We develop a theoretical model based on linear
elastic fracture mechanics to describe the propagation of such precursory slip.
The model's prediction of precursor lengths as a function of external load is
in good quantitative agreement with laboratory experiments as well as with
dynamic simulations, and provides thereby evidence to recognize frictional slip
as a fracture phenomenon. We show that predicted precursor lengths depend,
within given uncertainty ranges, mainly on the kinetic friction coefficient,
and only weakly on other interface and material parameters. By simplifying the
fracture mechanics model we also reveal sources for the observed non-linearity
in the growth of precursor lengths as a function of the applied force. The
discrete nature of precursors as well as the shear tractions caused by
frustrated Poisson's expansion are found to be the dominant factors. Finally,
we apply our model to a different, symmetric set-up and provide a prediction of
the propagation distance of frictional slip for future experiments
Fault constitutive relations inferred from the 2009-2010 slow slip event in Guerrero, Mexico
The spatiotemporal evolution of stress state is analyzed during the 2009-2010 Slow Slip Event (SSE) of Guerrero, Mexico, based on the kinematic inversion results and using an integral expression for stress changes. A linear slip weakening behavior is generally observed during the SSE with an average slope of -0.5 +/- 0.2 MPa/m regardless the perturbation due to the 27 February 2010 M-w = 8.8 Maule, Chile earthquake. This slope remains unchanged before and after the Maule earthquake. However, for some area, the friction behavior changes from slip hardening to slip weakening following the Maule earthquake. The complex trajectory between shear stress and slip velocity is fitted with a rate-and state friction law through an inversion. The direct (rate) effect (parameter A) is found to be very small, lower by an order of magnitude than the evolutional (state) effect (parameter B). The characteristic length L is obtained as 5 cm on average
The role of viscoelasticity on heterogeneous stress fields at frictional interfaces
We investigate the evolution of heterogeneous stress states along frictional in- terfaces. Using finite-element simulations, we model the occurrence of precur- sory slip sequences on a deformable-deformable as well as a deformable-rigid interface between two solids. Every interface rupture creates a stress concen- tration at its arrest position and erases the stress concentrations produced by previous slip events. While the interface is sticking perfectly between two slip events, erased stress concentrations reappear and survive several cycles of ruptures. Such reestablished stress concentrations are smaller than they were before the rupture. We show that the decrease rate of these stress concentrations is exponential with respect to the number of subsequent events and that the bulk viscoelasticity is at the origin of this history effect. During a slip event, the friction tractions at the interface change almost instantaneously, which leads, between two ruptures, to a relaxation-resembling viscous effect that restores the stress concentration. We describe the decrease rate analytically and highlight that it is proportional to the ratio of the viscous over the instantaneous Young’s moduli, and illustrate it by varying the material properties in our simulations
Slow slip detection with deep learning in multi-station raw geodetic time series validated against tremors in Cascadia
Slow slip events (SSEs) originate from a slow slippage on faults that lasts
from a few days to years. A systematic and complete mapping of SSEs is key to
characterizing the slip spectrum and understanding its link with coeval
seismological signals. Yet, SSE catalogues are sparse and usually remain
limited to the largest events, because the deformation transients are often
concealed in the noise of the geodetic data. Here we present the first
multi-station deep learning SSE detector applied blindly to multiple raw
geodetic time series. Its power lies in an ultra-realistic synthetic training
set, and in the combination of convolutional and attention-based neural
networks. Applied to real data in Cascadia over the period 2007-2022, it
detects 78 SSEs, that compare well to existing independent benchmarks: 87.5% of
previously catalogued SSEs are retrieved, each detection falling within a peak
of tremor activity. Our method also provides useful proxies on the SSE duration
and may help illuminate relationships between tremor chatter and the nucleation
of the slow rupture. We find an average day-long time lag between the slow
deformation and the tremor chatter both at a global- and local-temporal scale,
suggesting that slow slip may drive the rupture of nearby small asperities
Survival of Heterogeneous Stress Distributions Created by Precursory Slip at Frictional Interfaces
We study the dynamics of successive slip events at a frictional interface with finite-element simulations. Because of the viscous properties of the material, the stress concentrations created by the arrest of precursory slip are not erased by the propagation of the following rupture but reappear with the relaxation of the material. We show that the amplitude of the stress concentrations follows an exponential decay, which is controlled by the bulk material properties. These results highlight the importance of viscosity in the heterogeneous stress state of a frictional interface and reveal the “memory effect” that affects successive ruptures
Etude des séismes lents et du chargement intersismique dans la région de Guerrero au Mexique
Recent observations reveal the existence of different slip behaviors on fault, and among them the occurrence of transient aseismic slip events, the so-called slow slip events (SSEs). The general goal of this work is to understand the impact of slow slip events on the seismic cycle. The area of study is located in the southern Mexican subduction zone, around the Guerrero seismic gap. We use continuous GPS measurements of the ground displacements to model the slip on the subduction interface, using a dislocation model in an elastic half space. We can thus constrain the spatial and temporal evolution of two slow slip events (in 2006 and in 2009-2010), as well as the coupling ratio of the subduction interface. Our results highlight the differences in the spatio-temporal evolution of the two slow slip events : during the 2006 SSE, the slip propagated at a velocity of 1 km/day. The 2009-2010 SSE occurred in two sub-events and the second sub-event was triggered by the surface waves of the Maule earthquake (in Chili). Our results also show the lateral variations in the interseismic coupling of the subduction interface : the coupling ratio in the Guerrero gap being only 1/4 of the couling ratio on both sides of the gap. Most of the slip is thus accommodated by slow slip events in the Guerrero seismic gap.Les observations récentes ont mis en évidence la diversité des régimes de glissement des failles, et particulièrement l'existence de glissements asismiques transitoires, les séismes lents. Ce travail a pour objectif la compréhension de l'impact de ces séismes lents sur le cycle sismique. La zone étudiée correspond à la zone de subduction du sud du Mexique, au niveau de la lacune sismique de Guerrero. A partir de mesures de déplacement de surface, principalement par GPS, le glissement sur l'interface de subduction est modélisé par des dislocations dans un milieu élastique. Cette analyse nous permet de contraindre l'évolution spatio-temporelle de deux épisodes de glissements lent (2006 et 2009-2010), ainsi que le couplage de l'interface de subduction. Nos résultats montrent une certaine variabilité dans l'évolution spatio-temporelle des deux glissements étudiés : le séisme lent de 2006 présente clairement une propagation du glissement, à une vitesse d'environ 1 km/jour ; le séisme lent de 2009-2010 présente deux sous-évènements, l'occurrence du deuxième sous-évènement étant liée au déclenchement par le séisme de Maule au Chili. Nos résultats mettent également en évidence les variations latérales dans le couplage intersismique de l'interface de subduction : le couplage dans la lacune sismique de Guerrero étant 4 fois plus faible que le couplage de part et d'autre de la lacune. Ainsi la majeure partie du glissement est accommodée par les séismes lents dans la lacune sismique de Guerrero
Etude des séismes lents et du chargement intersismique dans la région de Guerrero au Mexique
Recent observations reveal the existence of different slip behaviors on fault, and among them the occurrence of transient aseismic slip events, the so-called slow slip events (SSEs). The general goal of this work is to understand the impact of slow slip events on the seismic cycle. The area of study is located in the southern Mexican subduction zone, around the Guerrero seismic gap. We use continuous GPS measurements of the ground displacements to model the slip on the subduction interface, using a dislocation model in an elastic half space. We can thus constrain the spatial and temporal evolution of two slow slip events (in 2006 and in 2009-2010), as well as the coupling ratio of the subduction interface. Our results highlight the differences in the spatio-temporal evolution of the two slow slip events : during the 2006 SSE, the slip propagated at a velocity of 1 km/day. The 2009-2010 SSE occurred in two sub-events and the second sub-event was triggered by the surface waves of the Maule earthquake (in Chili). Our results also show the lateral variations in the interseismic coupling of the subduction interface : the coupling ratio in the Guerrero gap being only 1/4 of the couling ratio on both sides of the gap. Most of the slip is thus accommodated by slow slip events in the Guerrero seismic gap.Les observations récentes ont mis en évidence la diversité des régimes de glissement des failles, et particulièrement l'existence de glissements asismiques transitoires, les séismes lents. Ce travail a pour objectif la compréhension de l'impact de ces séismes lents sur le cycle sismique. La zone étudiée correspond à la zone de subduction du sud du Mexique, au niveau de la lacune sismique de Guerrero. A partir de mesures de déplacement de surface, principalement par GPS, le glissement sur l'interface de subduction est modélisé par des dislocations dans un milieu élastique. Cette analyse nous permet de contraindre l'évolution spatio-temporelle de deux épisodes de glissements lent (2006 et 2009-2010), ainsi que le couplage de l'interface de subduction. Nos résultats montrent une certaine variabilité dans l'évolution spatio-temporelle des deux glissements étudiés : le séisme lent de 2006 présente clairement une propagation du glissement, à une vitesse d'environ 1 km/jour ; le séisme lent de 2009-2010 présente deux sous-évènements, l'occurrence du deuxième sous-évènement étant liée au déclenchement par le séisme de Maule au Chili. Nos résultats mettent également en évidence les variations latérales dans le couplage intersismique de l'interface de subduction : le couplage dans la lacune sismique de Guerrero étant 4 fois plus faible que le couplage de part et d'autre de la lacune. Ainsi la majeure partie du glissement est accommodée par les séismes lents dans la lacune sismique de Guerrero
Origin of the shallow slip deficit on a strike slip fault: Influence of elastic structure, topography, data coverage, and noise
International audienc
Etude des séismes lents et du chargement intersismique dans la région de Guerrero au Mexique
Recent observations reveal the existence of different slip behaviors on fault, and among them the occurrence of transient aseismic slip events, the so-called slow slip events (SSEs). The general goal of this work is to understand the impact of slow slip events on the seismic cycle. The area of study is located in the southern Mexican subduction zone, around the Guerrero seismic gap. We use continuous GPS measurements of the ground displacements to model the slip on the subduction interface, using a dislocation model in an elastic half space. We can thus constrain the spatial and temporal evolution of two slow slip events (in 2006 and in 2009-2010), as well as the coupling ratio of the subduction interface. Our results highlight the differences in the spatio-temporal evolution of the two slow slip events : during the 2006 SSE, the slip propagated at a velocity of 1 km/day. The 2009-2010 SSE occurred in two sub-events and the second sub-event was triggered by the surface waves of the Maule earthquake (in Chili). Our results also show the lateral variations in the interseismic coupling of the subduction interface : the coupling ratio in the Guerrero gap being only 1/4 of the couling ratio on both sides of the gap. Most of the slip is thus accommodated by slow slip events in the Guerrero seismic gap.Les observations récentes ont mis en évidence la diversité des régimes de glissement des failles, et particulièrement l'existence de glissements asismiques transitoires, les séismes lents. Ce travail a pour objectif la compréhension de l'impact de ces séismes lents sur le cycle sismique. La zone étudiée correspond à la zone de subduction du sud du Mexique, au niveau de la lacune sismique de Guerrero. A partir de mesures de déplacement de surface, principalement par GPS, le glissement sur l'interface de subduction est modélisé par des dislocations dans un milieu élastique. Cette analyse nous permet de contraindre l'évolution spatio-temporelle de deux épisodes de glissements lent (2006 et 2009-2010), ainsi que le couplage de l'interface de subduction. Nos résultats montrent une certaine variabilité dans l'évolution spatio-tempororelle des deux glissements étudiés : le séisme lent de 2006 présente clairement une propagation du glissement, à une vitesse d'environ 1 km/jour ; le séisme lent de 2009-2010 présente deux sous-évènements, l'occurrence du deuxième sous-évènement étant liée au déclenchement par le séisme de Maule au Chili. Nos résultats mettent également en évidence les variations latérales dans le couplage intersismique de l'interface de subduction : le couplage dans la lacune sismique de Guerrero étant 4 fois plus faible que le couplage de part et d'autre de la lacune. Ainsi la majeure partie du glissement est accommodée par les séismes lents dans la lacune sismique de Guerrero
Study of slow slip events and interseismic strain accumulation in the Guerrero regin, Mexico
Les observations récentes ont mis en évidence la diversité des régimes de glissement des failles, et particulièrement l'existence de glissements asismiques transitoires, les séismes lents. Ce travail a pour objectif la compréhension de l'impact de ces séismes lents sur le cycle sismique. La zone étudiée correspond à la zone de subduction du sud du Mexique, au niveau de la lacune sismique de Guerrero. A partir de mesures de déplacement de surface, principalement par GPS, le glissement sur l'interface de subduction est modélisé par des dislocations dans un milieu élastique. Cette analyse nous permet de contraindre l'évolution spatio-temporelle de deux épisodes de glissements lent (2006 et 2009-2010), ainsi que le couplage de l'interface de subduction. Nos résultats montrent une certaine variabilité dans l'évolution spatio-tempororelle des deux glissements étudiés : le séisme lent de 2006 présente clairement une propagation du glissement, à une vitesse d'environ 1 km/jour ; le séisme lent de 2009-2010 présente deux sous-évènements, l'occurrence du deuxième sous-évènement étant liée au déclenchement par le séisme de Maule au Chili. Nos résultats mettent également en évidence les variations latérales dans le couplage intersismique de l'interface de subduction : le couplage dans la lacune sismique de Guerrero étant 4 fois plus faible que le couplage de part et d'autre de la lacune. Ainsi la majeure partie du glissement est accommodée par les séismes lents dans la lacune sismique de Guerrero.Recent observations reveal the existence of different slip behaviors on fault, and among them the occurrence of transient aseismic slip events, the so-called slow slip events (SSEs). The general goal of this work is to understand the impact of slow slip events on the seismic cycle. The area of study is located in the southern Mexican subduction zone, around the Guerrero seismic gap. We use continuous GPS measurements of the ground displacements to model the slip on the subduction interface, using a dislocation model in an elastic half space. We can thus constrain the spatial and temporal evolution of two slow slip events (in 2006 and in 2009-2010), as well as the coupling ratio of the subduction interface. Our results highlight the differences in the spatio-temporal evolution of the two slow slip events : during the 2006 SSE, the slip propagated at a velocity of 1 km/day. The 2009-2010 SSE occurred in two sub-events and the second sub-event was triggered by the surface waves of the Maule earthquake (in Chili). Our results also show the lateral variations in the interseismic coupling of the subduction interface : the coupling ratio in the Guerrero gap being only 1/4 of the couling ratio on both sides of the gap. Most of the slip is thus accommodated by slow slip events in the Guerrero seismic gap
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