Volume 87, Number 4, August 2009
Article Number 48008
Number of page(s) 5
Section Interdisciplinary Physics and Related Areas of Science and Technology
Published online 08 September 2009
EPL, 87 (2009) 48008
DOI: 10.1209/0295-5075/87/48008

Determination of the scale of coarse graining in earthquake networks

S. Abe1, 2 and N. Suzuki3

1   Department of Physical Engineering, Mie University - Mie 514-8507, Japan
2   Institut Supérieur des Matériaux et Mécaniques Avancés - 44 F. A. Bartholdi, 72000 Le Mans, France, EU
3   College of Science and Technology, Nihon University - Chiba 274-8501, Japan

received 11 May 2009; accepted in final form 28 July 2009; published August 2009
published online 8 September 2009

In a recent paper (ABE S. and SUZUKI N., Europhys. Lett., 65 (2004) 581), the concept of earthquake network has been introduced in order to describe the complexity of seismicity. There, the cell size, which is the scale of coarse graining needed for constructing an earthquake network, has remained as a free parameter. Here, a method is presented for determining it based on the scaling behavior of the network. Quite remarkably, both the exponent of the power law connectivity distribution and the clustering coefficient are found to approach the respective universal values and remain invariant as the cell size becomes larger than a certain value, l*, which depends on the number of events contained in the analysis, in general. This l* fixes the scale of coarse graining. Universality of the result is demonstrated for all of the networks constructed from the data independently taken from California, Japan and Iran.

89.75.Da - Systems obeying scaling laws.
91.30.-f - Seismology.
05.65.+b - Self-organized systems.

© EPLA 2009