Conditional probability of surface rupture: A numerical approach for principal faulting

Abstract

This study presents a numerical approach for probabilistic fault displacement hazard analysis (PFDHA), aimed at addressing an alternative solution with commonly used empirical methodologies. Our model utilizes probability distributions to compute the conditional probability of surface rupture (CPSR). Leveraging earthquake catalogs, we derived the hypocentral depth distribution (HDD) across eight globally distributed seismotectonic regions categorized by faulting kinematics (normal, reverse, strike-slip). We calculated the hypocentral depth ratio (HDR) distribution, to model rupture position from the hypocenter. Employing magnitude scaling relations we determined rupture widths (W) spanning magnitudes 5–8. User-input parameters, including fault style, average dip angle, and seismogenic depth, with associated uncertainties, derive the CPSR estimation of surface rupture occurrences. Our findings highlight seismogenic depth as the most influential parameter and reveal correspondences between empirical curves derived for specific regions, emphasizing the importance of site-specific rupture probability assessments over global datasets and underscores the significance of considering seismotectonic context when evaluating fault displacement hazard. The numerical code for CPSR calculation has been developed and is openly accessible on GitHub.