“…Step 2 of PSHA often involves empirical analysis of existing data to determine ground motion (e.g., Boore et al, 1997). Various aspects of PSHA have been discussed by a number of authors, including the distinction between aleatory and epistemic uncertainty (Toro et al, 1997;Anderson and Brune, 1999;Anderson et al, 2000), use of synthetic earthquake catalogs (Ward, 1991(Ward, , 1996(Ward, , 2000, Monte Carlo methods (Savage, 1991(Savage, , 1992Cramer et al, 1996;Ebel and Kafka, 1999), and logic trees (Coppersmith and Youngs, 1986), application to fault rupture hazards (Youngs et al, 2003), and deaggregation of probabilistic results (Harmsen and Frankel, 2001).…”