Tsallis Entropy: A Non-Extensive Frequency-Magnitude Distribution of   Earthquakes
  By using the maximum entropy principle, with Tsallis entropy, we obtain an explicit dependence for energy distribution of earthquakes. This function describes very well the observations in a wide range of energies, where other distribution functions fail. We assume that the fragments filling the gap between the fault planes play an active role in the triggering of earthquakes. The energy distribution function is related to the size distribution function of these fragments. 
Oscar Sotolongo-Costa and Antonio Posadas