SONNE SO244/2

The majority of M>8.5 earthquakes (including Tohoku 2011, Sumatra 2004, 2005, 2007, Maule 2010 etc.) has hypocenters located beneath the oceans in subduction zones. Post-hoc analysis shows that most of the surface deformation related to co-seismic stress release takes place on the seafloor, in many cases unleashing major tsunamis. The seafloor thus stores crucial information on sub-seafloor processes, including stress, elastic strain, and earthquake and tsunami generation. This information is to be extracted through the nascent scientific field of seafloor geodesy by measuring acoustic distance, tilt and pressure for a duration of 3 years. The aim is to measure crustal deformation of cm scale using the GeoSEA array (Geodetic Earthquake Observatory on the SEAfloor).
The GeoSEA array will record deformation at the Iquique Segment of the Nazca-South America plate boundary, which has not ruptured since 1877. The array includes a self-steering autonomous surface vehicle (Wave Glider) which will receive acoustic information from the seafloor sensors and transmit them via satellite link to shore, allowing near realtime data transfer and system health monitoring.
The study will provide information about active tectonics of the offshore ocean shelf and trench, the degree of interseismic locking or creep, and the distribution of strain within the overriding plate.