Description: Submarine slope failures are a widespread, hazardous phenomenon on continental margins. The prevailing opinion links large submarine landslides along the glaciated NW European continental margins to overpressure generated by the alternation of rapidly deposited glacigenic and hemipelagic material. Here, we report a newly discovered large landslide complex off NW Svalbard. It differs from all known large slides off NW Europe, as the available data rule out that this slope failure resulted from rapid glacigenic deposition. This suggests that processes such as contour currents, tectonic faulting, and overpressure build-up related to the gas hydrate system must be considered for hazard assessment.

Description: The cruise AL527 took place in the Western Baltic Sea in the period 6. – 14.09.2019. The cruise was carried out as a marine geophysical field course of Kiel University, supported by BONUS ECOMAP project. Starting and ending point of the cruise was Kiel. One stopover in Kiel took place during the cruise due to an exchange of parts of the scientific party (10.09.2019). The main aim of the cruise was to introduce marine geophysical acquisition to the students including hands-on experience in collecting marine geophysical data. This approach also included a first processing and interpretation of the data as well as the presentation of the first results. Two areas in the Western Baltic Sea were the main working areas of AL527. The first survey area was at Boknis Eck, a part of the Eckernförde Bay. The main objective in this area was to search for an underwater observatory from the Coastal Observing System for Northern and Arctic Seas Project (COSYNA), which was operated by GEOMAR and disappeared end of August 2019. For this purpose, a survey with a bathymetric multibeam system from the ”Marine Geophysics and Hydroacoustics” working group (Kiel University) was carried out. Furthermore, an underwater camera system was used for visual inspections. The second survey area was in the Mecklenburger Bay. The main objective was a pre-investigation of a buried beach for an upcoming cruise within the EU-funded project ACT-SENSE. Therefore, 2D reflections seismic, sediment echo sounder, and multibeam data were acquired. Additionally, 7 gravity cores were taken for ground trothing and sampling of the buried beach. In order to analyze major tectonic structures in the Fehmarn Belt and the Mecklenburger Bay, 12 additional seismic profiles were collected when transiting between the survey areas. Our investigations showed that a buried beach is located in the Mecklenburger Bay beneath a layer of mud. The sand deposits have an estimated variable thickness between 1m and 9m in the survey area. The top of the beach was successfully sampled with several gravity cores. Further investigations of these cores, together with the geophysical data, will be take place in the frame of the ACT-SENSE project. In the acquired bathymetric dataset from Boknis Eck some conspicuous zones could be identified, where possibly remaining parts of the missing underwater observatory are located. Unfortunately, it was not possible to validate these zones by the used underwater camera. These zones should be investigated by divers in the near future, for a reliable validation.

Description: The cruise AL542 took place in the Western Baltic Sea in the period 14. – 21.08.2020. The cruise was carried out as a marine geophysical field course of Kiel University. Starting and ending point of the cruise was Kiel. One stopover in Kiel took place during the cruise due to an exchange of parts of the scientific party (18.08.2020). The main aim of the cruise was to introduce marine geophysical acquisition to the students including hands-on experience in collecting marine geophysical data. This approach also included a first processing and interpretation of the data as well as the presentation of the first results. The main survey area of the first leg of the cruise AL 542 was the Bay of Mecklenburg. In the eastern part of the bay seismic and acoustic data were collected with the aim to identify historical coastlines and buried glacial structures. Further, the central part of the bay was mapped with the multibeam echosounder to find the Blinkerhügel, a small mound with reported accumulation of manganese nodules, investigated in 2002 by Hlawatsch et al. The Blinkerhügel was clearly identified as an outcropping ground moraine. Seafloor samples at eight locations were collected with a grab from the area of the Blinkerhügel. At one location stones with manganese crusts were successfully retrieved. The four survey areas of the second leg of the cruise were Mittelgrund, Noer and Damp which are located in the Eckernförde Bay and an area near Fehmarn which is located in the northwest of the island in the Fehmarn Sund. In the region Mittelgrund in the Eckernförde Bay a wellknown, developing pockmark field was surveyed with hydroacoustic and seismic methods. Furthermore, a known pockmark near Noer was surveyed with hydroacoustic methods. From the third survey area Damp Laminaria agitate algae have been reported. The aim in this area was to check, if it is possible to detect the algae with the hydroacoustic systems. Additionally, some video transects and seafloor samples were gathered for ground truthing in this region. In the survey area near Fehmarn a dynamic dune field was surveyed with hydroacoustic methods. This dune field is surveyed every year to document changes in the submarine environment.

Description: Three Pleistocene giant slope failures are observed in high-resolution bathymetric and seismic reflection data off Southern Chile, two of which extend across the full width of the continental slope from the shelf break to the trench. With mobilized volumes between 253 km3 and 472 km3, these slides are among the largest submarine landslides documented at active continental margins so far. Deposits of each of the slides are imaged as chaotic sequences in seismic reflection lines buried beneath well-stratified sediments in the Chile Trench. The ages of the three slides are about 0.25, 0.41 and .0.56 Ma. The main preconditioning factor for the slope instabilities seems to be local uplift of the continental slope that results in peculiarly high slope angles of up to 308. Uplift of the marine and continental forearc of the study area is the result of shortening across upper plate faults and therefore a long-term continuous process. Slope instability seems to be an iterative process and failure is likely to recur.