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Common dependence on stress for the statistics of granular avalanches and earthquakes.

Hatano T, Narteau C, Shebalin P - Sci Rep (2015)

Bottom Line: The faulting style dependence may be related to the magnitude of the differential stress, but no model so far has been able to reproduce this behaviour.Here we investigate the statistical properties of avalanches in a dissipative, bimodal particulate system under slow shear.These results are consistent with recent seismological observations of earthquake size-distribution and aftershock statistics.

View Article: PubMed Central - PubMed

Affiliation: Earthquake Research Institute, University of Tokyo, 113-0032 Tokyo, Japan.

ABSTRACT
Both earthquake size-distributions and aftershock decay rates obey power laws. Recent studies have demonstrated the sensibility of their parameters to faulting properties such as focal mechanism, rupture speed or fault complexity. The faulting style dependence may be related to the magnitude of the differential stress, but no model so far has been able to reproduce this behaviour. Here we investigate the statistical properties of avalanches in a dissipative, bimodal particulate system under slow shear. We find that the event size-distribution obeys a power law only in the proximity of a critical volume fraction, whereas power-law aftershock decay rates are observed at all volume fractions accessible in the model. Then, we show that both the exponent of the event size-distribution and the time delay before the onset of the power-law aftershock decay rate are decreasing functions of the shear stress. These results are consistent with recent seismological observations of earthquake size-distribution and aftershock statistics.

No MeSH data available.


Related in: MedlinePlus

A conceptual model of a fault zone using a 3D granular system.We consider that the fault zone is a strongly damaged area that may be investigated through granular mechanics. The granular model represents a thin gouge layer. The constant grain size, the relatively high porosity and the low grain size to system size ratio of the model do not capture the natural structural and compositional complexities of fault zones in nature. Despite these strong differences, we explore similarities between the dynamics of avalanches in the model and earthquakes.
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f1: A conceptual model of a fault zone using a 3D granular system.We consider that the fault zone is a strongly damaged area that may be investigated through granular mechanics. The granular model represents a thin gouge layer. The constant grain size, the relatively high porosity and the low grain size to system size ratio of the model do not capture the natural structural and compositional complexities of fault zones in nature. Despite these strong differences, we explore similarities between the dynamics of avalanches in the model and earthquakes.

Mentions: Because the shear stress along an active fault is not directly measurable, a solution to address stress dependences in earthquake statistics is to analyse models that implement a restricted set of physical processes. Such models are indeed numerous, ranging from rock fracture experiments6789 to computer simulations on cellular automata1011. Among them, sheared granular media1213141516171819 are simple representations of granular fault gouges (Fig. 1), which are commonly used in geophysics to analyse deformation of highly damaged rocks in fault zones202122. Additionally, both the energy and the stress can be easily defined in these models.


Common dependence on stress for the statistics of granular avalanches and earthquakes.

Hatano T, Narteau C, Shebalin P - Sci Rep (2015)

A conceptual model of a fault zone using a 3D granular system.We consider that the fault zone is a strongly damaged area that may be investigated through granular mechanics. The granular model represents a thin gouge layer. The constant grain size, the relatively high porosity and the low grain size to system size ratio of the model do not capture the natural structural and compositional complexities of fault zones in nature. Despite these strong differences, we explore similarities between the dynamics of avalanches in the model and earthquakes.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4508663&req=5

f1: A conceptual model of a fault zone using a 3D granular system.We consider that the fault zone is a strongly damaged area that may be investigated through granular mechanics. The granular model represents a thin gouge layer. The constant grain size, the relatively high porosity and the low grain size to system size ratio of the model do not capture the natural structural and compositional complexities of fault zones in nature. Despite these strong differences, we explore similarities between the dynamics of avalanches in the model and earthquakes.
Mentions: Because the shear stress along an active fault is not directly measurable, a solution to address stress dependences in earthquake statistics is to analyse models that implement a restricted set of physical processes. Such models are indeed numerous, ranging from rock fracture experiments6789 to computer simulations on cellular automata1011. Among them, sheared granular media1213141516171819 are simple representations of granular fault gouges (Fig. 1), which are commonly used in geophysics to analyse deformation of highly damaged rocks in fault zones202122. Additionally, both the energy and the stress can be easily defined in these models.

Bottom Line: The faulting style dependence may be related to the magnitude of the differential stress, but no model so far has been able to reproduce this behaviour.Here we investigate the statistical properties of avalanches in a dissipative, bimodal particulate system under slow shear.These results are consistent with recent seismological observations of earthquake size-distribution and aftershock statistics.

View Article: PubMed Central - PubMed

Affiliation: Earthquake Research Institute, University of Tokyo, 113-0032 Tokyo, Japan.

ABSTRACT
Both earthquake size-distributions and aftershock decay rates obey power laws. Recent studies have demonstrated the sensibility of their parameters to faulting properties such as focal mechanism, rupture speed or fault complexity. The faulting style dependence may be related to the magnitude of the differential stress, but no model so far has been able to reproduce this behaviour. Here we investigate the statistical properties of avalanches in a dissipative, bimodal particulate system under slow shear. We find that the event size-distribution obeys a power law only in the proximity of a critical volume fraction, whereas power-law aftershock decay rates are observed at all volume fractions accessible in the model. Then, we show that both the exponent of the event size-distribution and the time delay before the onset of the power-law aftershock decay rate are decreasing functions of the shear stress. These results are consistent with recent seismological observations of earthquake size-distribution and aftershock statistics.

No MeSH data available.


Related in: MedlinePlus