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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

Typical time series of the elastic energy for a constant shear rate  and different volume fraction ϕ:(top) ϕ = 0.630, (middle) ϕ = 0.644, (bottom) ϕ = 0.650. As shown by the normalization constant of the vertical axes, the total energy and the energy releases explore different ranges of magnitude according to volume fraction. Inset in the middle panel shows how we estimate the energy release associated with a single avalanche.
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f2: Typical time series of the elastic energy for a constant shear rate and different volume fraction ϕ:(top) ϕ = 0.630, (middle) ϕ = 0.644, (bottom) ϕ = 0.650. As shown by the normalization constant of the vertical axes, the total energy and the energy releases explore different ranges of magnitude according to volume fraction. Inset in the middle panel shows how we estimate the energy release associated with a single avalanche.

Mentions: As observed in many previous works on amorphous particulate systems1415161720212324252627282930, Fig. 2 shows that the temporal fluctuations of the energy becomes volatile if the shear rate is sufficiently low and the volume fraction is sufficiently high. Under such condition the kinetic energy is negligible in comparison with the elastic energy E(t), and therefore the elastic energy drop should approximate a transition from a local maximum to a local minimum in configurational energy. Then, an avalanche is defined as an abrupt drop of the elastic energy, E(t1) − E(t2), where t1 and t2 denote the beginning and the end of an event, respectively. This is illustrated in the inset of Fig. 2b.


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

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

Typical time series of the elastic energy for a constant shear rate  and different volume fraction ϕ:(top) ϕ = 0.630, (middle) ϕ = 0.644, (bottom) ϕ = 0.650. As shown by the normalization constant of the vertical axes, the total energy and the energy releases explore different ranges of magnitude according to volume fraction. Inset in the middle panel shows how we estimate the energy release associated with a single avalanche.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f2: Typical time series of the elastic energy for a constant shear rate and different volume fraction ϕ:(top) ϕ = 0.630, (middle) ϕ = 0.644, (bottom) ϕ = 0.650. As shown by the normalization constant of the vertical axes, the total energy and the energy releases explore different ranges of magnitude according to volume fraction. Inset in the middle panel shows how we estimate the energy release associated with a single avalanche.
Mentions: As observed in many previous works on amorphous particulate systems1415161720212324252627282930, Fig. 2 shows that the temporal fluctuations of the energy becomes volatile if the shear rate is sufficiently low and the volume fraction is sufficiently high. Under such condition the kinetic energy is negligible in comparison with the elastic energy E(t), and therefore the elastic energy drop should approximate a transition from a local maximum to a local minimum in configurational energy. Then, an avalanche is defined as an abrupt drop of the elastic energy, E(t1) − E(t2), where t1 and t2 denote the beginning and the end of an event, respectively. This is illustrated in the inset of Fig. 2b.

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