During the RV SONNE cruise SO278, which took place between 2020-10-12 to 2020-12-01 bathymetry data based on multibeam echosounder (MBES) was recorded. Investigations on mud volcanoes were carried out in four working areas: the Sartori mud volcano in the Calabrian Arc, the Cobblestone Area, the Olimpi Mud Volcano Field and the United Nation Ridge. The hull-mounted KONGSBERGER EM122 multibeam echosounder systems was used in the areas of interest. This echosounder system uses nominal sounding frequencies of 10.5 to 13 kHz and was therefore used in water depth of more than 700 m. 288 beams with an acoustical footprint of 0.5°(TX)/1°(RX) are formed for each ping. Due to the use of the high-density equidistant and dual swath mode 864 soundings can be received with each ping. During the cruise the swath width was set to 120° and partly to 130°. For further information consult https://www.km.kongsberg.com/. During the SO278 due to a problem the pre-amplifier unit has been turned off and the resolution had to be reduced to RX=2°. The system worked from then on, however,the dual swath mode could not be used as half of the swath would have gaps every second ping. The data recorded the first days of the cruise revealed therefore relatively bad quality. Although from this modification on the system worked stable and produced better bathymetric data, the water column was continuously noisy, especially in the central sectors, which clearly limited the possibility to detect water column anomalies. Nevertheless over 3580 nautical miles in Italian and Greek waters have been mapped.Sound velocity profiles (SVP) were applied on the data for data calibration. SVP raw data are part/not part of this dataset publication.

These data should not be used for navigational purposes.Responsible persons during this cruise / PI: Miriam Römer & Stefanie