The FocusX1 oceanographic expedition is the seafloor experiment of the ambitious FOCUS project, an ERC Advanced Grant entitled FOCUS (Fiber Optic Cable Use for Seafloor studies of earthquake hazard and deformation) funded by the EU for 3.5 M€ over 5 years. The goal is to develop and test a new technique to monitor seafloor deformation through use of fiber optic cables in order to improve hazard assessment and increase early warning capability. Laser reflectometry using BOTDR, commonly used for structural health monitoring of large-scale engineering structures (e.g. - bridges, dams, pipelines, etc.), can measure very small strains (< 1 mm) at very large distances (10 - 200 km). It has never been used to monitor deformation caused by active faults on the seafloor.

The goal of this project is to demonstrate that this technique can measure small (1 - 2 cm) displacements on a primary test site offshore Sicily where the 25 km long Catania cable crosses the recently mapped North Alfeo Fault. The main objective of the planned marine expedition is the connection and deployment of a dedicated 6-km long seafloor fiber optic strain cable using an ROV. First we planned to perform a 2-day video-camera survey of the seafloor along the trace of the cable and along and across the submarine fault. Then we deployed and connected a Y-splice junction box, to the cabled seafloor observatory Catania Test Site South (TSS) station in 2050 m water depth. Next we deployed a 6-km long fibner-optic strain cable using a custom made plow, operated by the ROV Victor6000 to bury the cable 20cm below the seafloor. Finally, we planned to deploy 8 seafloor geodetic instruments in order to provide an independent measure of seafloor deformation.