Citation

Lippiello E, Corral A, Bottiglieri M, Godano C, de Arcangelis L. Phys. Rev. E Stat. Nonlin. Soft Matter Phys. 2012; 86(6-2): 066119.

Affiliation

Department of Mathematics and Physics and CNISM, Second University of Naples, 81100 Caserta, Italy.

Copyright

(Copyright © 2012, American Physical Society, Publisher American Institute of Physics)

DOI

unavailable

PMID

23368016

Abstract

We present a study of the earthquake intertime distribution D(Δt) for a California catalog in temporal periods of short duration T. We compare experimental results with theoretical predictions and analytical approximate solutions. For the majority of intervals, rescaling intertimes by the average rate leads to collapse of the distributions D(Δt) on a universal curve, whose functional form is well fitted by a Gamma distribution. The remaining intervals, exhibiting a more complex D(Δt), are all characterized by the presence of large shocks. These results can be understood in terms of the relevance of the ratio between the characteristic time c in the Omori law and T: Intervals with Gamma-like behavior are indeed characterized by a vanishing c/T. The above features are also investigated by means of numerical simulations of the Epidemic Type Aftershock Sequence (ETAS) model. This study shows that collapse of D(Δt) is also observed in numerical catalogs; however, the fit with a Gamma distribution is possible only assuming that c depends on the main-shock magnitude m. This result confirms that the dependence of c on m, previously observed for m>6 main shocks, extends also to small m>2.

Language: en