The Fraunhofer Institute for Wind Energy Systems IWES has completed a boulder detection campaign off the coast of the island of Rügen in the German Baltic Sea on behalf of 50Hertz.
In order to allow efficient planning of the grid operator’s new offshore platform seismic measuring techniques have been employed to detect boulders below the seafloor in. This process allows identification of large rocks up to 100 m below the seafloor. Scientist from Fraunhofer IWES used the Manta Ray G1 measuring system to perform the measurements. The measuring system comprises a towed array equipped with seismic sensors (hydrophones) as well as positioning systems. During the survey of an area, the hydrophones pick up the reflected sound waves previously emitted by a signal source. This allows the subseafloor to be recorded step-by-step and mapped in three dimensions. The measuring system maps the sediment layers, and enables the detection of boulders buried in the seafloor.