Aboard Polarstern, bathymetry — the mapping of the seafloor using sonar — is conducted by an international working group. In recent days, they have found a distinct elevation at the seafloor of the Southern Ocean. This structure rises 600 m above ground in an otherwise featureless seascape and is situated about 450 km north of the Antarctic continent. It closely resembles an underwater volcano, presumably still active, which has never been charted on a map. This finding was reported by Elena Pugacheva from the Geographical Institute Moscow and Jan-Hendrik Lott from the University of Karlsruhe.

During the expedition, long distances are covered between the continents of Africa, Antarctica and South America. Mapping of the seafloor takes place throughout the journey when crossing uncharted waters. The Russian Academy of Sciences is a contributor to this international mapping project.

The bathymetry project requires a multi-beam echo sounder integrated into the ship’s hull. An acoustic signal is sent to the bottom of the sea, where it is reflected by the sea floor and received by a sensor on the ship. The time it takes for the signal to travel through the water column and back allows for the computation of precise depths. Complex computer technology is required, especially to visualise the data in real-time as depicted in the picture.

The entire dataset at the end of such research cruises is fed into an international database, where it used to constantly update existing charts of the world’s oceans. The resulting charts allow for safer navigation also through Antarctic waters, especially shallow waters on the continental shelf.

Should the newly discovered structure be confirmed to be an underwater volcano, it would demonstrate once again that the deep-sea floor is not featureless, nor constant. The investigation of the dynamics of the seafloor is crucial to the further development of the modified theory of continental drift by Alfred Wegener, after whom the Alfred Wegener Institute is named.

Text by Angelika Dummermuth
Photo credit: Armin Rose