Olami-Feder-Christensen model with quenched disorder

We study the Olami-Feder-Christensen model with quenched disorder in the coupling parameter alpha . In contrast to an earlier study by Mousseau [Phys. Rev. Lett. 77, 968 (1996)], we do not find a phase diagram with several phase transitions, but continuous crossovers from one type of behavior to another. The crossover behavior is determined by the ratio of three length scales, which are the system size, the penetration depth of the boundary layer, and the correlation length introduced by the disorder.