SONNE SO297

The proposed PISAGUA cruise aims to derive a detailed high-resolution model for the marine forearc in Northern Chile to image the forearc of an erosional subduction zone. One main target is to compare the forearc structure to previous and ongoing accumulation of seismic moment. Therefore, the project composes an amphibious 2D and 3D refraction seismic experiment in Northern Chile offshore Taltal to investigate the control of incoming and overriding plate structures on earthquake rupture behavior. This subduction zone segment in the region offshore Taltal, where a mature seismic gap is located, ruptured in 1922 during a major earthquake and is poorly known from marine observations. The highresolution structural 2D and 3D images obtained in this project, together with data from the seismic stations onshore, will be used to investigate the control of upper and lower plate structure on coupling and other rheological parameters. It is planned to complement the experiment with seismological stations onshore (Universidad de Concepción). Furthermore, we install novel drift-free pressure sensors (A-0-A type) capable of measuring water pressure changes without drift. This new kind of observation allows resolving subsidence and sea-level changes with a precision better than 1 cm for more than five years.