Seismic imaging of the seismogenic coupling zone. A seismic survey is performed in January 2005 comprising a 3C near-vertical reflection profile including an expanding spread profile as well as a specially designed generation of S-waves. The target is the seismogenic coupling zone of the 1960 Valdivia earthquake down to a depth of about 50 km. We are interested in the structural properties related to the subduction channel and the corresponding processes (in particular pore-pressure and stress evolution, friction, compaction, lithification, dehydration).