Understanding the factors leading to large earthquakes in the coupling zone of convergent margins and their interrelation with surface deformation are the main aims of the international and interdisciplinary research initiative TIPTEQ (From The Incoming Plate To megaThrust EarthQuake Processes). Between Nov. 2004 and Oct. 2006 we deployed 2 temporary, amphibious seismic arrays in South-Central Chile. The northern network between 37 and 39S was formed by up to 120 digitally recording land stations and 10 Ocean Bottom Seismometers/Hydrophones (OBS/OBH). The southern network located between 41.5 and 43.5S at and around Chiloe Island was formed by 20 land stations and 20 OBS/OBH stations. Applied methods: 3-D velocity models (tomography), receiver functions, teleseismic tomography, moment tensor inversion, geological interpretation (among others).