Criticality in the Burridge-Knopoff model.

Criticality is a potential origin of the scale invariance observed in the Gutenberg-Richter law for earthquakes. In support of this hypothesis, the Burridge-Knopoff (BK) model of an earthquake fault system is known to exhibit a dynamic phase transition, but the critical nature of the transition is uncertain. Here it is shown that the BK model exhibits a dynamic transition from large-scale stick-slip to small-scale creep motion and through a finite size scaling analysis the critical nature of this transition is established. The order parameter describing the critical transition suggests that the Olami-Feder-Christensen model may be tuned to criticality through its assumptions describing the relaxation of the system.