Description: Agadir Canyon is one of the largest submarine canyons in the World, supplying giant submarine sediment gravity flows to the Agadir Basin and the wider Moroccan Turbidite System. While the Moroccan Turbidite System is extremely well investigated, almost no data from the source region, i.e. the Agadir Canyon, are available. Understanding why some submarine landslides remain as coherent blocks of sediment throughout their passage downslope, while others mix and disintegrate almost immediately after initial failure, is a major scientific challenge, which was addressed in the Agadir Canyon source region during Cruise MSM32. We collected ~ 1500 km of seismic 2D-lines in combination with a dense net of hydroacoustic data. About 1000 km2 of sea floor were imaged during three deployments of TOBI (deep-towed sidescan sonar operated by the National Oceanography Centre Southampton). A total of 186 m of gravity cores and several giant box cores were recovered at more than 50 stations. CTD casts were collected at nine stations including one 13 hour Yo-yo CTD. The new data show that Agadir canyon is the source area of the world's largest submarine sediment flow, which occurred about 60,000 years ago. Up to 160 km3 of sediment was transported to the deep ocean in a single catastrophic event. For the first time, sediment flows of this scale have been tracked along their entire flow pathway. A major landslide area was identified south of Agadir Canyon. Landslide material enters Agadir canyon in about 2500 m water depth; the material is transported as debrite for at least another 200 km down the canyon. Initial data suggest that the last major slide from this source entered Agadir canyon at least 130,000 years ago. Living deep-water corals were recovered from a large mound field north of Agadir canyon. To our knowledge, these are the first living cold water corals recovered off the coast of Morocco (except for the Gulf of Cadiz). They represent an important link between the known cold-water coral provinces off Mauritania and in the Gulf of Cádiz.

Description: The NW African continental margin is well known for the occurrence of large-scale but infrequent submarine landslides. The aim of this paper is to synthesize the current knowledge on submarine mass wasting off NW Africa with a special focus on the distribution and timing of large landslides. The described area reaches from southern Senegal to the Agadir Canyon. The largest landslides from south to north are the Dakar Slide, the Mauritania Slide, the Cap Blanc Slide, the Sahara Slide and the Agadir Slide. Volumes of individual slides reach several hundreds of cubic kilometres; run-outs are up to 900 km. In addition, giant volcanic debris avalanches are widespread on the flanks of the Canary Islands. All headwall areas are complex with clear indications of multiple failures. The most prominent similarity between all investigated landsides is the existence of widespread glide planes that follow the stratigraphy, which points to weak layers as most important preconditioning factor for the failures. Landslides with volumes larger than 100 m3 are close to being evenly distributed over time, contradicting previous suggestions that landslides off NW Africa occur at periods of low or rising sea level. The risk associated with the landslides off NW Africa, however, is relatively low due to their long recurrence rates.

Description: Summary The continental margins of southern Italy are located along converging plate boundaries, which are affected by intense seismicity and volcanic activity. Most of the coastal areas experienced severe earthquakes, landslides, and tsunamis in historical and/or modern times. The most prominent example is the Messina earthquake of Dec. 28, 1908 (Ms=7.3; 80,000 casualties), which was characterized by the worst tsunami Italy experienced in the historical time (~2000 casualties). It is, however, still unclear, whether this tsunami was triggered by a sudden vertical movement along a major fault during the earthquake or as a result of a giant marine slide initiated by the earthquake. The recurrence rates of major landslides and therefore the risk associated with landslides is also unknown. Based on detailed bathymetric data sets collected by Italian colleagues in the frame of the MaGIC Project (Marine Geohazards along the Italian Coast), we collected seismic data (2D and 3D) and gravity cores in three working areas (The Messina Straits, off Eastern Sicily, the Gioia Basin). A dense grid of new 2D-seismic data in the Messina Straits will allow to map fault patterns in great detail. One interesting outcome in this context is the identification of a set of normal faults striking in an EW-direction, which is almost perpendicular to the previously postulated faults. This EW-striking faults seem to be active. The area off eastern Sicily is characterized by numerous landslides and a complex deformation pattern. A 3D-seismic data set has been collected during the cruise using the so called P-cable in order to investigate these deformation patterns in detail. The new data will be the basis for a risk assessment in the working areas.

Description: Submarine geomorphology underwent significant development in the second half of the 20 th century, largely thanks to advances in technology by the military, navigation and hydrocarbon industry, which were later transferred to the academic and commercial sectors. In this chapter we summarise the development of the key methods used in submarine geomorphology between 1950 and 2000, which include sidescan sonar, multibeam echosounder, reflection seismology, seafloor sampling and marine robotic systems. We then highlight the progress in our understanding of seafloor processes and landforms made using these methods, focusing on continental shelf landforms, slope instability, submarine canyons, submarine fans and channels, and current-controlled landforms.