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Main & Al-Kindy 2002
Main, I.G. and Al-Kindy, F.H. (2002). Entropy, energy, and proximity to criticality in global earthquake populations. Geophysical Research Letters 29: doi: 10.1029/2001GL014078. issn: 0094-8276.

We examine the question of proximity of the global earthquake population to the critical point characterised by the energy E and entropy S based on annual frequency data from the Harvard CMT catalogue. The results are compared with a theoretical model corresponding to a Boltzmann probability density distribution of the form p(E) ∝ E-B-1e-E. The data are consistent with the model predictions for fluctuations in the characteristic energy θ at constant B value, of the form S~B⟨lnE⟩. This approximation is valid for large θ, relative to the maximum possible event size, confirming that the Earth is perpetually in a near-critical state, reminiscent of self-organized criticality. However, the results also show fluctuations of ¿10% in entropy that may be more consistent with the notion of intermittent criticality. A more precise definition of the two paradigms, and a similar analysis of numerical models, are both needed to distinguish between these competing models.

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Abstract

Keywords
Mathematical Geophysics, Nonlinear dynamics, Seismology, Seismic hazard assessment and prediction, Seismology, Earthquake dynamics and mechanics, Seismology, Theory and modeling
Journal
Geophysical Research Letters
http://www.agu.org/journals/gl/
Publisher
American Geophysical Union
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