19 pages, 7 figures, 4 tables, A geomorphological analysis of the submarine landslides geographical information system catalogue of the Geological Survey of Spain has revealed three main groups of submarine landslides associated with (1) deep-ocean seamount ridges (extinct spreading centres), (2) volcanic islands and (3) continental margins. These three groups have statistically significant morphometric differences, as determined from analysis of variance (ANOVA) and Tukey's HSD Tests, in total length (runout), total area, maximum deposit width and bathymetric depth. Volcanic island-related slope failures affect larger areas of the seafloor and their headwall escarpments often extend above sea-level. Slope failures associated with seamount ridges are the deepest, between 3500 and 5500 m, and display relatively high width-to-length ratios. Finally, landslides on continental margins show two sub-groups. Landslides on tectonically controlled margins have smaller runouts and total area and larger average slope gradients than margins where tectonic controls are limited. These results demonstrate that submarine landslide morphology is strongly controlled by the geological-tectonic setting, This work has been supported by the EU-funded projects GARAH (GeoERA GE-1), EMODnet High Resolution Seabed Mapping (EASME/EMFF/2015/1.3.1.7/SI2.74125) and EMODnet Bathymetry–High Resolution Seabed Mapping (EASME/EMFF/2018/007). Funding was provided by the ‘Ministerio de Ciencia, Innovación y Universidades’ and the European Regional Development Fund through project INSIGHT (CTM2015-70155-R), Peer reviewed

12 pages, 8 figures, 2 tables, The development of overpressure in continental margins is typically evaluated with hydrogeological models. Such approaches are used to both identify fluid flow patterns and to evaluate the development of high pore pressures within layers with particular physical properties that may promote slope instability. In some instances, these models are defined with sediment properties based on facies characterization and proxy values of porosity; permeability or compressibility are derived from the existing literature as direct measurements are rarely available. This study uses finite-element models to quantify the differences in computed overpressure generated by fine-grained hemipelagic sediments from the Gulf of Cadiz, offshore Martinique and the Gulf of Mexico, and their consequences in terms of submarine slope stability. By comparing our simulation results with in situ pore pressure data measured in the Gulf of Mexico, we demonstrate that physical properties measured on volcanic-influenced hemipelagic sediments underestimate the computed stability of a submarine slope. Physical properties measured on sediments from the study area are key to improving the reliability and accuracy of overpressure models, and when that information is unavailable, literature data from samples with similar lithologies, composition and depositional settings enable better assessment of the overpressure role as a pre-conditioning factor in submarine landslide initiation, Davide Mencaroni was supported by a Marie Skłodowska-Curie Doctoral Fellowship through the SLATE Innovative Training Network within the European Union Framework Programme for Research and Innovation Horizon 2020 under Grant Agreement No. 721403. The Spanish ‘Ministerio de Economia y Competitividad’ and the European Regional Development Fund through grant CTM2015-70155-R (project INSIGHT) are also acknowledged, Peer reviewed