Investigating subduction zone processes in Chile

The highly active subduction zone of southern Chile was the source region of the 1960 Valdivia megathrust earthquake ( M w = 9.5), the largest earthquake ever recorded.This region is currently under investigation by the multidisciplinary TIPTEQ (From the Incoming Plate to Mega‐Thrust Earthquake Processes) project, which is studying the structure, state, and deformation of the subduction zone lithosphere. Over 90 days, from December 2004 to February 2005,TIPTEQ scientists on cruise S0181 of the German research vessel (R/V Sonne acquired a broad variety of geophysical and geological data in the research area offshore Chile between 35°S and 48°S (Figure 1).These data include active and passive source seismics, heat flow probing, magnetics, magnetotellurics for studying Earth conductivity, highresolution multibeam bathymetry, and sediment probes from gravity cores.