We present an analysis of a slider block model of an earthquake fault which indicates the presence of metastable states ending in spinodals. We identify four parameters whose values determine the size and statistical distribution of the {open_quotes}earthquake{close_quotes} events. For values of these parameters consistent with real faults we obtain scaling of events associated not with critical point fluctuations but with the presence of nucleation events. {copyright} {ital 1997} {ital The American Physical Society}