Repeating Earthquakes in Northern Chile

Northern Chile was described as a seismic gap due to the lack of large seismicity in more than a 100 years. Recently, another large subduction earthquake (Mw 8.1) released part of the accumulated energy in the area. Due to the anticipation produced by this activity, a large seismological network deployed at the site successfully recorded this event. This network is composed by a wide variety of instruments, ranging from strong-motion accelerograms, broadbands, and continuous GPS. This wide variety of instruments enabled a detailed study of this large event, as well as the precursory activity and subsequent aftershock events. This enormously rich database has been used to detect repeating earthquakes, interpreted as aseismic slip along the plate boundary and strongly linked to large subduction earthquakes. In the present study, we search for repeating events in the plate boundary, as well as within the subducting slab (intermediate-depth intraplate earthquakes) using reported clusters in the area, previously identified with standard techniques, extending the observational time window to ~2008. We use a methodology successfully applied to interplate events in this area: using the clusters' waveforms as a template, we search for repeating events in the continuous data. We believe that these findings will improve our current knowledge of the seismic sequences of large interplate and intermediate-depth intraplate earthquakes.