Nonextensive models for earthquakes
  We have revisited the fragment-asperity interaction model recently introduced by Sotolongo-Costa and Posadas (Physical Review Letters 92, 048501, 2004) by considering a different definition for mean values in the context of Tsallis nonextensive statistics and introducing a new scale between the earthquake energy and the size of fragment $\epsilon \propto r^3$. The energy distribution function (EDF) deduced in our approach is considerably different from the one obtained in the above reference. We have also tested the viability of this new EDF with data from two different catalogs (in three different areas), namely, NEIC and Bulletin Seismic of the Revista Brasileira de Geof\'{\i}sica. Although both approaches provide very similar values for the nonextensive parameter $q$, other physical quantities, e.g., the energy density differs considerably, by several orders of magnitude. 
R. Silva (on-MCT & Uern), G. S. Franca (UFRN), C. S. Vilar (UFRN), J.   S. Alcaniz (on-MCT)