INTERACTION BETWEEN SUBDUCTION ZONE PROCESSES AND INTRAPLATE FAULTS ALONG THE CHILEAN COAST

Major subduction zone earthquakes occur regularly along the Nazca-South America plate boundary off the coast of Chile. While these earthquakes pose great risk to the Chilean population, events occurring along crustal faults in coastal regions also present a threat. Though the maximum earthquake magnitude on these intraplate faults is smaller than that of megathrust earthquakes, and the recurrence interval is long, the proximity of these faults to population centers requires that they be considered in developing a complete seismic hazard assessment. We explore the potential activity of these crustal faults by modeling their interactions with subduction zone earthquake cycle processes using the boundary element method. We estimate stress accumulation rates on the crustal faults due to interseismic strain accumulation across the plate boundary and use these stressing rates to infer long-term fault slip rates. Preliminary results suggest that stressing rates on crustal faults in northern and central Chile are similar, but the morphological expression of the faults varies along the coastline owing to differences in climate, among other factors. We investigate the effects induced on intraplate faults by spatially variable interseismic coupling and seismic segmentation on the megathrust and compare modeled fault slip rates to sparse paleoseismic observations.