The Anillo is a dense temporary seismic and geodetic network extending approximately 200 km along the strike of the subduction zone in North Chile in order to investigate how earthquakes and aseismic slip scale over a broader spectrum of source sizes, to understand the complex relationships between seismic and aseismic deformation, and to identify possible structural controls. This experiment is embedded into a larger scale experimental effort carried out by institutions in Germany and Chile. Waveform data are available from the GEOFON data centre, under network code Y6.