Seismic Hazard Assessment of the San Ramón Fault in Santiago, Chile

Abstract The Chilean seismic activity consists mainly of interface and inslab earthquakes caused by the subduction of the Nazca Plate beneath the South American Plate. Nonetheless, several shallow crust faults also contribute to the seismic hazard in the country. An example of such faults is the San Ramón Fault (SRF), an active shallow crust system located at the eastern border of Santiago, whose seismic activity has recently been discovered. The SRF has an average slip rate of 0.4 mm/year, and it has the potential to generate earthquakes with magnitudes up to [[EQUATION]]. Although previous studies have examined the seismic hazard posed by the fault, a probabilistic approach has not been undertaken. This research compares the seismic hazard posed by the subduction zone with that generated by the SRF in Santiago, using state-of-the-art models that represent their geometry and seismicity. We compute seismic hazard maps employing deterministic and probabilistic approaches to assess the influence of the SRF on the study zone. Resulting hazard maps from a deterministic analysis present areas where the intensities caused by an earthquake on the SRF are over three times greater than those from interface and inslab events. However, under a probabilistic approach, the hazard of the SRF is less than 3% that of the subduction zone, attributed to the fault's large return period. Finally, our results indicate that the influence of the SRF on Santiago's seismic hazard strongly depends on the intensity measure considered.