Abstract

Although smaller and less recurrent than earthquakes occurring on the interplate contact of subduction margins, seismic events on crustal faults (fault reactivation) may cause severe damage for inhabited areas in the vicinity. Former studies suggest that fault reactivation may occur during the interseismic phase (the time period between two successive earthquakes) of the subduction cycle or following megathrust earthquakes. This is, both phases may induce stress perturbations on crustal faults and, eventually, produce their reactivation. Herein, we calculate the stress perturbations induced by interseismic and coseismic scenarios on seismogenic crustal faults in the northern Chile outer forearc (19°S–23°S). These faults occur directly above a subduction segment that contained the great 1877 Iquique Earthquake. Our results suggest that both interseismic and coseismic stages of the megathrust cycle may produce fault reactivation; nevertheless, each stage favors specific fault types. Furthermore, our results indicate that a great megathrust earthquake in the area could promote the reactivation of most of the upper crustal faults, increasing the seismic hazard in the region. This study is relevant when considering the interaction between interplate processes and crustal fault reactivation to better assess the seismic hazard in this and other subduction zones.