10.34691/FK2/91GHJE Pastén, Franciscohttps://orcid.org/0000-0001-9318-0343(Universidad de Chile) Repositorio de datos de investigación de la Universidad de Chile 2022 doi:10.34691/FK2/91GHJE/H9RTQOdoi:10.34691/FK2/91GHJE/WJ33KKdoi:10.34691/FK2/91GHJE/EIPNEXdoi:10.34691/FK2/91GHJE/VP1UYBdoi:10.34691/FK2/91GHJE/HLS5QUdoi:10.34691/FK2/91GHJE/8RWJI8doi:10.34691/UCHILE/6HTLNX/CJTCOO The subduction of different features such as oceanic ridges, fractures zones or seamounts are important for the accurate characterization of subduction zones. These structures may affect the along-dip variability of seismic behavior and eventually trigger slow earthquakes. Here we studied the along- dip influence of the Copiapó ridge subduction in the Atacama region, North-Central Chile, an area where seismic swarms, low coupling values and slow earthquakes have been reported. We built a seismic catalog including repeating earthquakes and non-volcanic tremors (NVT), and performed a 3-D tomography for P-wave velocity and Vp/Vs ratio. We identify along-dip segmentation involving 4 distinct segments: (1) a locked seismogenic zone (20 to 35 km depth), hosting ordinary clustered micro-seismicity and repeating earthquakes; (2) a transition zone (35 to 42 km) with non-volcanic tremor and low seismicity; (3) a zone (42 to 60 km) without seismicity and with slow-slip events and (4) a deep zone with more abundant seismicity. The velocity models show differences among these zones: while low velocity anomalies of Vp and Vs, and Vp/Vs ratio between 1.76 and 1.82 are observed in the deep zone, higher velocities are present in the other areas. These features indicate that SSE are located in a zone with higher pore fluid pressure. We propose that these geodynamic differences are generated by the subduction of heterogenic seamounts associated to the Copiapó ridge. Pastén, Francisco(Universidad de Chile)Potin, Bertrand(Universidad de Chile)Azúa, Kellen(Universidad de Chile)Ruiz, Sergio(Universidad de Chile)