Quantifying the role of MAss WAsting in submarine CAnyons on Active and Passive margins 

Expedition:          SO310, 20.02.2025 – 22.03.2025
Project duration:  01.10.2024 – 31.03.2027
Coordination:      GEOMAR, FB4, GDY
Coordinator:        Jörg Bialas
Project partner:   CAU Kiel, IfG, MG, Sebastian Krastel
                           GNS, Neuseeland, Christof Müller
                           NIWA, Neuseeland, Joshu Mountjoy
                           GSI, Israel, Oded Katz

Submarine canyons incise active and passive continental margins around the world. They are highly dynamic submarine systems forming complex seafloor structures. Turbidity currents and mass wasting are dominant processes in formation of canyon topography. Canyon head and flank failures often progress upslope forming retrogressive terraces. Usually being located close to populated areas, such failures in canyons do have a hazard potential to settlement and submarine installations. Canyons have been investigated in active and passive margin settings but direct comparisons based on field data are rare. The MAWACAAP joint project in New Zealand uses the spatial proximity of Palliser Canyon, in the area of influence of subduction on the Hikurandi continental margin, and Pegasus Canyon, away from the subduction zone, for such a comparison. We propose to develop frequency-volume relationships of landslides in canyons with special focus on systematic differences between active and passive margin settings. In addition, we will investigate factors controlling the size and location of failures including topographic amplification effects of canyons for earthquake waves. The integrated analysis of the data shall lead to an improved assessment of hazards and risks related to sediment failures in canyons at active and passive margins.

Analyses of stability criteria for slope failure processes by numerical modelling will be the major task of GEOMAR. The new 2D and 3D field data will provide the basis for the stratigraphy of the models. Existing data will be used as far as possible. OBS investigations will provide velocity-depth distributions and geotechnical analyses of sheer strength and compressibility of sediment samples as well as age dating will be integrated. Investigations on geometrical focusing of earthquakes in canyon systems will be supported.

32 participants from the partner institutes set off on February 20, 2025 on the RV SONNE from the port of Wellington, New Zealand on expedition SO310 to collect the necessary field data.