Statistical analysis of synthetic earthquake catalogs generated by models with various levels of fault zone disorder

The stress release model, a stochastic version of the elastic rebound theor y, is applied to the large events from four synthetic earthquake catalogs g enerated by models with various levels of disorder in distribution of fault zone strength (Ben-Zion, 1996) They include models with uniform properties (U), a Parkfield-type asperity (A), fractal brittle properties (F), and mu lti-size-scale heterogeneities (M). The results show that the degree of reg ularity or predictability in the assumed fault properties, based on both th e Akaike information criterion and simulations, follows the order U, F, A, and M, which is in good agreement with that obtained by pattern recognition techniques applied to the full set of synthetic data. Data simulated from the best fitting stress release models reproduce, both visually and in dist ributional terms, the main features of the original catalogs. The differenc es in character and the quality of prediction between the four cases are sh own to be dependent on two main aspects: the parameter controlling the sens itivity to departures from the mean stress level and the frequency-magnitud e distribution, which differs substantially between the four cases. In part icular, it is shown that the predictability of the data is strongly affecte d by the form of frequency-magnitude distribution, being greatly reduced if a pure Gutenburg-Richter form is assumed to hold out to high magnitudes.