  We present theoretical arguments and simulation data indicating that the
scaling of earthquake events in models of faults with long-range stress
transfer is composed of at least three distinct regions. These regions
correspond to three classes of earthquakes with different underlying physical
mechanisms. In addition to the events that exhibit scaling, there are larger
``breakout'' events that are not on the scaling plot. We discuss the
interpretation of these events as fluctuations in the vicinity of a spinodal
critical point.
