ABSTRACT
We present a very brief review of recent findings about scale-invariant behavior in the structure of earthquake occurrence in time and size, leading to the proposal of a striking universal scaling law that has also been shown to describe fracture phenomena. The range of validity of this law in space and energy is enormous. Previously, we discuss the concepts of self similarity and scale invariance and relate them with power laws and scaling laws, explaining the difference between them. The connections between critical phenomena, crackling noise, self-organized criticality, and the possible existence of universality and universality classes out-of-equilibrium are mentioned as well.
