The Guadiaro-Baños contourite drifts (SW Mediterranean). A geotechnical approach to stability analysis

• DOI: 10.1016/j.margeo.2021.106505
• Publication Date: 2021-05-11T16:19:12Z
• Authors: M. Yenes; D. Casas; J. Nespereira; N. López-González; D. Casalbore; S. Monterrubio; B. Alonso; G. Ercilla; C. Juan; P. Bárcenas; D. Palomino; P. Mata; P. Martínez-Díaz; N. Pérez; J.T. Vázquez; F. Estrada; M. Azpiroz-Zabala; M. Teixeira
• Keywords: Contourite; Seafloor Spreading; Submarine landslide

Two Quaternary plastered contourite drifts, with terraced and low-mounded morphologies, make up the continental slope base-of-slope in northwestern Alboran Sea, respectively, between Guadiaro Baños turbidite systems, close to Strait of Gibraltar. Considering their significant lateral extent, link drift deposits landslides may be particularly important for hazard assessment. The physical properties, composition geometry drifts have been proposed as key factors stability, although this relationship still needs better constrained. In work, new in-situ geotechnical data (cone penetration tests; CPTu) has combined morphostratigraphic, sedimentological, (laboratory) properties determine stability Guadiaro-Baños drifts. For depositional domains both resulting sedimentary model describes low-plasticity granular silty sands on erosive domain that evolve seawards silty-clay a higher plasticity uniform geomechanical properties. shallower coarse-grained sediments, cohesion (c') internal friction angle (ϕ') values are 0–9 kPa 46–30°, whereas distal fine contourites undrained shear strength gradient (∇Su) is 2 kPa/m. These allow us establish high safety all scenarios considered, including seismic loading. Slope failure triggered unlikely event there acceleration PGA > 0.19, no potential glide planes observed within first 20 m below seafloor. This suggests studied tend resist than others similar characteristics. interplay several processes explain enhanced strength: 1) defined by an upper contouritic terrace lower shapes; 2) recurrent low-intensity earthquakes insufficient energy trigger landslides, favouring increased due dynamic compaction; 3) cyclic loading induced solitons/internal waves acting sediment.