A probabilistic displacement hazard assessment framework for distributed ruptures from strike-slip earthquakes

Widespread distributed fracturing during earthquakes threatens infrastructure and lifelines. We combine high-resolution rupture maps from the five major surface-rupturing strike-slip earthquakes in southern California and northern Mexico since 1992 to incorporate the displacements produced by secondary ruptures into a probabilistic displacement hazard analysis framework. Through analysis of the spatial distribution of mapped ruptures and displacements for each of these events, we develop a magnitude-dependent expression for the probability per unit area of finding a secondary rupture that accommodates a displacement that exceeds a displacement threshold at a given distance away from the principal fault. Our model is best applied to estimating expected secondary displacements for strike-slip earthquakes, similar to those analyzed, with widespread ruptures across immature fault zones.