Abstract
The Gutenberg‐Richter power law distribution for energy released at earthquakes can be understood as a consequence of the earth crust being in a self‐organized critical state. A simple cellular automaton stick‐slip type model yields D(E) ≈ E−τ with τ≈1.0 and τ≈1.35 in two and three dimensions, respectively. The size of earthquakes is unpredictable since the evolution of an earthquake depends crucially on minor details of the crust.