The Gulf of Vera (Western Mediterranean) presents a complex geomorphology that is the result of the sedimentary response to the Aguilas tectonic indentation Arc in the framework of the Eurasian–Africa plate collision. This indentation has caused the quasi-continuous oversteepening of the entire margin, which has favored the gravitational instability of the 97% of its seafloor. This margin is one of the most affected by mass movements in the SW Mediterranean Sea. With a characteristic instability of 0.356 km2 and a mean volume of 0.0108 km3, the continental slope shows moderate events comparable to those of other Mediterranean areas.The Aguilas high is one of the structural highs shaping the margin. Its top is characterized by a smooth surface shaped by sedimentary deposits (contourites). Those deposits are affected on the southern edge by a pockform field, erosive features (scars) and deposits with the characteristic ridges of spreading processes.The aim of this work is to define from morphological and geotechnical point of view the instabilities observed on the summit of the high as well as to evaluate the role of fluid flow over those instability processes. Different data set have been merged and combined, including very high-resolution bathymetric data, gravity cores and in-situ geotechnical data (CPTu tests).The results obtained define a geotechnical weak interval at depths between 10 and 15 m below seafloor which is compatible with a detachment surface where lateral spreads developed. The processes would be driven by liquefaction (cyclic softening) triggered by seismic events that affects the clayey sediments present on the stratigraphic record. This process may also favour the vertical fluid flow due to overpressure that may explain the pockform field observed. The spatial association between pockforms and scars observed, evidence a strong link between liquefaction, fluid flow and instability in the study area. This research was funded by the Spanish MCIN/AEI/10.13039/501100011033. Grant PID2022-138258OB-I00 (inGRAVITAS).

In this work, over 3620 km2 2 from the Palomares continental slope, which is located in the W. Mediterranean Sea, was analysed to quantify the impact of recent mass movements on this margin. A total of 936 landslides were identified, mapped and characterised by defining several morphometric variables that outline the accumulated impact of landslides equivalent to 918 km2 2 and 10.34 km3 3 of eroded sediment on the continental slope. The smallest event area was 0.0014 km2, 2 , whereas the largest event area was 32.48 km2. 2 . Smaller scars with a higher headwall gradient tend to dominate when the environment is steeper, and major mass movements are located on open slopes and structural highs. However, the slight or null correlations between variables indicate that a wide range of sizes may occur on any slope gradient and at any depth. The Palomares continental slope is intensively affected by mass movements. Compared with other passive margins (e.g., the U.S. Atlantic continental margin), landslides mobilised a limited amount of sediment, although it is comparable to other Mediterranean areas where small- to moderate-sized events are characteristic. The cumulative size distribution can be defined by a power-law function that describes events larger than 0.7 km2 2 with an exponent of alpha = 1.269. These results are consistent with those of other published inventories, including onshore cases. This result allows us to assume that the scale-invariant properties of the events are mapped. Scale-invariant properties can be explained by different models; self-organised criticality (SOC) is probably the most assumed by the scientific community, although alternative models may be nominated. Each model has important implications in terms of the landslide distribution and long-term landslide history of any slope. Alternative scenarios, such as submarine slopes, with more precise landslide inventories may contribute to new hazard assessment models that consider scaling exponents derived from size-frequency distributions.

This work aims to establish the role of liquefaction in a shallow submarine environment defined by a canyon head reaching the coast. The study area is the Garrucha submarine canyon head, which is located in the western Mediterranean Sea. The potential of liquefaction is approached empirically by two methods in parallel, undrained cyclic direct simple shear (UCDSS) test and piezocone penetration test (CPTu) analyses. For both approaches, considering the regional earthquake records, a cyclic load linked to Mw <= 6.5 earthquake events or a maximum ground surface acceleration amaxof max of 0.25 g is considered. The sediment samples analysed are nonplastic sands with low silt/clay contents and can be defined as liquefiable. Geotechnical analysis reveals a high probability of triggering liquefaction in this kind of sediment at depths greater than 3 m below the seafloor. CPTu records are used to assess and improve the liquefaction model for the study area by defining 3 different stratigraphic configurations or liquefiable conditions: uniformly liquefiable, interbedded liquifiable and nonliquefiable. This work highlights the importance of liquefaction-a process normally underestimated in submarine environments-in the downslope transport of sediment from the upper part of a canyon and, more generally, in canyon head evolution with different potential morphosedimentary consequences.

The Sines Contourite Drift (SCD) is a plastered drift with terraced-like morphology, formed by the Mediterranean Outflow Water (MOW) that emplaced in the Alentejo Margin, SW Iberia. The high ( 27 cm/kyr) and variable sedimentation rates experienced since the Pleistocene resulted in low consolidation, and the development of excess pore pressure, which, associated with the seismicity in SW Iberia, offer significant conditions for slope instability in the SCD’s Late Pleistocene-Holocene muddy-contourite and hemipelagic sediments. Therefore, it is crucial to assess the susceptibility of the area to submarine landslide hazards. Slope instability is assessed both under static and transient conditions, based on the sediment mechanical properties, obtained through drained and undrained triaxial tests performed on sediment samples of three gravity cores (CO14-GC-2B, CO14-GC-3B, and CO14-GC-7B), respectively, retrieved at 1208-, 1280-, and 1425-m water depth (mwd). Those properties consist of internal friction angle ( ϕ ' ), with average values ranging between 28.5° and 35.1°; sediment unit weight ( γ ) that ranges from 16.9 to 18.1 kN/m 3 ; and undrained shear strength ( S u ), ranging between 5.81 and 6.50 kPa. Cohesion ( c ' ) values are incipient and thus considered as 1 kPa in the modeling under static conditions. The analysis also accounts for the peak ground acceleration (PGA), determined according to the magnitude of seismicity recorded in the area. The SCD is prone to slope instability and collapse, especially in gradients > 5°, due to the sediment’s low consolidation, strength, and permeability. Seismicity greatly reduces the factor of safety (FS), promoting slope instability.

Several water masses are involved in the circulation of oceans, their bottom layers impacting on sedimentation through contourites. The majority of palaeoceanographic studies on regional contourites are performed for one water mass despite that their joint study would offer relevant clues to understand past ocean and climate interaction. This works presents for the first time a an analysis about the impact of the Light Intermediate Mediterranean (LMW) and Dense Deep Mediterranean (DMW) bottom currents on the sedimentation in the Alboran Sea (SW Mediterranean) and its paleoceanographic significance in response to climatic oscillations from the last glacial period to the Holocene. To do this, an integration of chronostratigraphical, sedimentological, and compositional data is carried out from contourites formed by those water masses. That integration enable us to define three distinct contourite stratigraphic models. (I) The contourite terrace model, characterized by coarse-grained contourites, which is an archive of the interplay between the high-energy Atlantic Water-LMW interface and glacioeustasy from the Younger Dryas (YD) to the Holocene. (II) The contourite drift models, which are archives of rapid ocean-climate coupled fluctuations since 29.5 kyr. They comprise coarse-grained contourites formed by a relatively fast LMW and fine-grained contourites formed by a relatively weak DMW, except for the Heinrich Stadials HS3 to HS1 and YD when coarse-grained contourites were deposited. (III) The contourite/turbidite mixed model represents another archive of DMW and glacioeustasy interplay from the end of the late Pleistocene to Holocene. That contourite stratigraphy allows us to infer for the first time the relative variability of the LMW versus DMW flow regimes, which records differences and similarities. The similarities indicate that the LMW and DMW fluctuations occur in parallel at millennial and centennial time scales. The differences refer to the overall higher velocity of LMW versus DMW; the magnitude changes in velocities that are lower for LMW and higher for DMW; the recognition of three short ventilation events (a, b, c) during HS1 and HS2 for only DMW; and the distinct LMW and DMW responses to the onset of glacial conditions and return to interglacial conditions during the HSs, YD and Holocene cold periods. The proposed contourite stratigraphic models can be applied for other areas in the Mediterranean margins to identify and correlate the LMW and DMW palaeoceanographic events throughout this sea. The findings suggest that the different water masses that make up the water column must be seriously considered to fully understand palaeoceanographic and palaeoclimatic studies based on contourites. This is because their distinct impact on sedimentation may provide new insights into their different palaeoceanographic responses to rapid climatic oscillations and their triggering mechanisms.

During the MVSEIS-08 cruise of 2008, ten new mud volcanoes (MVs) were discovered on the offshore Moroccan continental margin (Gulf of Cádiz) at water depths between 750 and 1,600 m, using multibeam bathymetry, backscatter imagery, high-resolution seismic and gravity core data. Mud breccias were recovered in all cases, attesting to the nature of extrusion of these cones. The mud volcanoes are located in two fields: the MVSEIS, Moundforce, Pixie, Las Negras, Madrid, Guadix, Almanzor and El Cid MVs in the western Moroccan field, where mud volcanoes have long been suspected but to date not identified, and the Boabdil and Al Gacel MVs in the middle Moroccan field. Three main morphologies were observed: asymmetric, sub-circular and flat-topped cone-shaped types, this being the first report of asymmetric morphologies in the Gulf of Cádiz. Based on morpho-structural analysis, the features are interpreted to result from (1) repeated constructive (expulsion of fluid mud mixtures) and destructive (gravity-induced collapse and submarine landsliding) episodes and (2) interaction with bottom currents.

The Holocene morpho-stratigraphic evolution of a compound submarine deltaic system linked with the Antas and Almanzora Rivers on the narrow (< 5 km) shelf along the Palomares margin (southeastern Iberia) has been reconstructed from the integrated analysis of geomorphology, seismo-stratigraphy and sedimentology. The shelf morphology is characterized by a 3-4 km wide deltaic body off the Almanzora River, where seafloor undulations and gullies are present. Larger and more incised gullies, crescent-shaped bedforms and pockmarks are recognizable at or close to the head of shelf-indenting canyons associated with the Almanzora-Garrucha canyon system. The seismo-stratigraphy displays a strong and irregular basal reflector overlain by a sedimentary wedge, showing variable thicknesses (1-25 m) and seismic characteristics along and across the shelf. The main depocenter of this wedge is not located off the Almanzora River mouth (i.e., the main sedimentary input in the study area) but along the southern shelf encompassing the Almanzora and Antas Rivers. Grain-size and sand compositional analyses show that silty sand with high terrigenous content (mostly quartz and mica) is mainly found on the submarine deltaic body. In contrast, sandy silt with variable ratios between terrigenous and biogenic contents is retrieved from the canyon head and associated gullies as well as from the surrounding mid-outer shelf. The evolution of the Antas-Almanzora compound delta has been divided into three evolutionary stages, mainly driven by the interplay between paleo-topography and riverine and marine processes and modulated by sea level changes during the Holocene. The origin of the present-day morphological features is also discussed, again highlighting a complex interaction between sedimentary gravity flows (mainly flash flood-generated hyperpycnal flows), storm-waves and shelf currents, fluid seepage and retrogressive slope failures.

We present a multidisciplinary study of morphology, stratigraphy, sedimentology, tectonic structure, and physical oceanography to report that the complex geomorphology of the Palomares continental margin and adjacent Algerian abyssal plain (i.e., Gulf of Vera, Western Mediterranean), is the result of the sedimentary response to the Aguilas Arc continental tectonic indentation in the Eurasian–Africa plate collision. The indentation is imprinted on the basement of the margin with elongated metamorphic antiforms that are pierced by igneous bodies, and synforms that accommodate the deformation and create a complex physiography. The basement is partially covered by Upper Miocene deposits sealed by the regional Messinian Erosive Surface characterized by palaeocanyons that carve the modern margin. These deposits and outcropping basement highs are then covered and shaped by Plio-Quaternary contourites formed under the action of the Light Intermediate and Dense Deep Mediterranean bottom currents. Even though bottom currents are responsible for the primary sedimentation that shapes the margin, 97% of this region's seafloor is affected by mass-movements that modified contourite sediments by eroding, deforming, faulting, sliding, and depositing sediments. Mass-movement processes have resulted in the formation of recurrent mass-flow deposits, an enlargement of the submarine canyons and gully incisions, and basin-scale gravitational slides spreading above the Messinian Salinity Crisis salt layer. The Polopo, Aguilas and Gata slides are characterized by an extensional upslope domain that shapes the continental margin, and by a downslope contractional domain that shapes the abyssal plain with diapirs piercing (hemi)pelagites/sheet-like turbidites creating a seafloor dotted by numerous crests. The mass movements were mostly triggered by the interplay of the continental tectonic indentation of the Aguilas Arc with sedimentological factors over time. The indentation, which involves the progressively southeastward tectonic tilting of the whole land-sea region, likely generated a quasi-continuous oversteepening of the entire margin, thus reducing the stability of the contourites. In addition, tectonic tilting and subsidence of the abyssal plain favoured the flow of the underlying Messinian Salinity Crisis salt layer, contributing to the gravitational instability of the overlying sediments over large areas of the margin and abyssal plain.

This article offers an overview of the main sedimentary systems defining the geomorphology of deep sea environments from low to high latitudes. Mass-transport deposits, turbidite systems, contourites, volcaniclastic aprons, glacial trough mouth systems, carbonate mounds and other bathyal systems, such as pelagites, hemipelagites, mid-ocean channels and polymetallic mineral deposits, are presented with special attention to their morphology, sediments, processes and controlling factors. The integration of the main systems on the continental margins and adjacent abyssal plains in the North Atlantic and westernmost Mediterranean allows to characterize different sedimentation models.

The Gulf of Cadiz and the Alboran Sea are characterized by tectonic activity due to oblique convergence at the boundary between the Eurasian and Nubian plates. This activity has favored a variety of tsunamigenic sources: basically, seismogenic faults and submarine landslides. The main tsunamigenic faults in the Gulf of Cadiz would comprise the thrust systems of Gorringe Ridge, Marquês de Pombal, São Vicente Canyon, and Horseshoe faults with a high susceptibility; meanwhile in the Alboran Sea would be the thrust system of the northern Alboran Ridge with high susceptibility, and the thrust systems of north Xauen and Adra margin, the transpressive segment of Al Idrissi fault, and the Yusuf-Habibas and Averroes faults, with moderate to high susceptibility. The areas with the greatest potential to generate tsunamigenic submarine landslides are in the Gulf of Cadiz, the São Vicente Canyon, Hirondelle Seamount, and Gorringe Ridge; and in the Alboran Sea are the southern and northern flanks of Alboran Ridge. Both sources are likely to generate destructive tsunamis in the Gulf of Cadiz, given its history of bigger earthquakes (>7 Mw) and larger landslides. To fully assess tsunamigenic sources, further work needs to be performed. In the case of seismogenic faults, research focus on geometry, offsets, timing, paleoearthquakes, and recurrence, and in landslides on early post-failure evolution, age, events, and recurrence. In situ measurements, paleotsunami records, and long-term monitoring, in addition to major modeling developments, will be also necessary.

A modelling approach to understand the tsunamigenic potentiality of submarine landslides will provide new perspectives on tsunami hazard threat, mostly in polar margins where global climatic change and its related ocean warming may induce future landslides. Here, we use the L-ML-HySEA (Landslide Multilayer Hyperbolic Systems and Efficient Algorithms) numerical model, including wave dispersion, to provide new insights into factors controlling the tsunami characteristics triggered by the Storfjorden LS-1 landslide (southwestern Svalbard). Tsunami waves, determined mainly by the sliding mechanism and the bathymetry, consist of two initial wave dipoles, with troughs to the northeast (Spitsbergen and towards the continent) and crests to the south (seawards) and southwest (Bear Island), reaching more than 3 m of amplitude above the landslide and finally merging into a single wave dipole. The tsunami wave propagation and its coastal impact are governed by the Storfjorden and Kveithola glacial troughs and by the bordering Spitsbergen Bank, which shape the continental shelf. This local bathymetry controls the direction of propagation with a crescent shape front, in plan view, and is responsible for shoaling effects of amplitude values (4.2 m in trough to 4.3 m in crest), amplification (3.7 m in trough to 4 m in crest) and diffraction of the tsunami waves, as well as influencing their coastal impact times.

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

The Western Mediterranean Deep Water (WMDW), on its way out toward the Atlantic Ocean, has favored the formation of contourite drifts in the Alboran Sea (SW Mediterranean) since the opening of the Strait of Gibraltar. Resolving the nature of these deposits is crucial for reconstructing the WMDW variability at a millennial scale, deciphering its bottom current paleo-velocity, and establishing paleoclimatic implications over the last 25 cal. kyr BP. Two sediment cores retrieved from elongated separated and plastered contourite drifts formed along its path are investigated by means of multi-sedimentological data (terrigenous grain-size, sortable silt, terrigenous and carbonate sediment fluxes, bioturbation and ichnofabric changes), geochemical data (Zr/Al and Si/(Si + Al) ratios), chronostratigraphic data (delta O-18, and C-14 data) as well as statistical analyses (grain-size end-member modelling and spectral analysis). Integration of these data confirms the contouritic nature of Alboran drift deposits. The high-resolution paleocurrent records of the WMDW inferred from the sortable silt of contourite sequences led us to define two regimes in terms of WMDW flow energy. Regime 1 (weak to moderate velocity) defined by paleo-velocities of similar to 4 to 23 cm s(-1) is dominant during the last 24 cal kyr BP. Regime 2 (strong velocity) is characterized by estimated paleo-velocities of about similar to 36 cm s(-1) during Heinrich Stadial 2. The spectral analysis of bottom current proxies (sortable silt and Zr/Al ratio) matches four cyclic climatic signals (1900 yr, 2300 yr, 4000 ye and 6100 yr), corroborating the occurrence of millennial-scale cyclicity. These cycles are related to atmospheric climate variability, in turn linked to variations in solar activity. Our results, when combined with published data from a neighboring NW Mediterranean contourite drift, provide for a better regional understanding of the WMDW millennial-scale dynamics.

The seafloor of the Alboran Sea reflects its complex tectonic, sedimentary, and oceanography dynamics as a consequence of the geological context, involving interaction between the Eurasian and African plates, and oceanographic context, as it is where the Atlantic and Mediterranean waters meet. Their physiography has a semi-enclosed configuration characterized by two margins (the Spanish Iberian and North Africa—mostly Moroccan margins) enclosing deep basins. Tectonic activity is mainly attested by folds and faults that predominantly affect the central and eastern seafloor sectors, as well as numerous seamounts and fluid-flow features (pockmarks, mud volcanoes, and diapirs) that dot the seafloor. The sedimentary and oceanographic processes allow us to distinctly define two principal environments in the Alboran Sea: the shallow proximal margin (continental shelf); and the deep distal margin (continental slope and base of the slope) with the adjacent sub-basins. The shelf mostly comprises prodeltaic and infralittoral prograding wedges, with local bedform fields, submarine valleys, and wave-cut terraces. Coastal and fluvio-marine sedimentary processes, acting since the last glacial period, are responsible for these features. The deep marine environment is characterised by the ubiquity of contourites, whose continuity is interrupted by turbidite systems, canyons, and landslides. The alongslope action of the Mediterranean waters and their interfaces with the Atlantic water has been the main process governing transport, seafloor reworking, and sedimentation of contourites. Mass-movement processes are responsible for the formation of: (1) turbidite systems—turbidity flows and mass flows were dominant during the last glacial sea-level lowstand, evolving to dilute gravity flows during present interglacial high stand; and (2) landslides—the main triggering factors comprising over-steepening, seismicity, under consolidation due to overpressure by interstitial fluids, stratigraphy, and high sedimentation rates. Locally, still-undetermined biological activity in the Spanish and coral activity in the Moroccan margin generated fields of mounded bioconstructions. The seafloor morphology of the Alboran Sea offers interesting clues for assessing the main potential geological hazards, with tectonic seismicity and landslides (as well as their related tsunamis) being some of the most important potential hazards affecting coastal populations. In addition, the seafloor morphology in combination with assemblages of habitat-forming species enables habitat identification and mapping.

Offshore geological hazards can occur in any marine domain or environment and represent a serious threat to society, the economy, and the environment. Seismicity, slope sedimentary instabilities, submarine volcanism, fluid flow processes, and bottom currents are considered here because they are the most common hazardous processes; tsunamis are also examined because they are a secondary hazard generated mostly by earthquakes, slope instabilities, or volcanic eruptions. The hazards can co-occur and interact, inducing a cascading sequence of events, especially in certain contexts, such as tectonic indentations, volcanic islands, and canyon heads close to the coast. We analyze the key characteristics and main shortcomings of offshore geological hazards to identify their present and future directions for marine geoscience investigations of their identification and characterization. This review establishes that future research will rely on studies including a high level of multidisciplinarity. This approach, which also involves scientific and technological challenges, will require effective integration and interplay between multiscale analysis, mapping, direct deep-sea observations and testing, modelling, and linking offshore observations with onshore observations.

In recent years, apparent overconsolidation (AOC) has been observed in the most superficial sections of the sedimentary column of the seabed. AOC has been detected in sediment samples taken from deep and shallow waters, independent of the source area. Although the origin of this phenomenon remains controversial, it seems to be linked principally to physical-chemical bonds and ionic changes that cause strong attractions between particles. This work uses an experimental approach based on standardized oedometer tests to study the presence of AOC in surface sediments and its disappearance at depth. The results obtained show that the existence of AOC is related to the formation of a structured sediment generated by both secondary consolidation and aging processes. In addition, the results obtained facilitate a discussion of how AOC influences the potential development of plane translational slides. The development of this type of instability in areas affected by AOC generates a subsequent stabilization of the ocean floor and, consequently, a lower recurrence of large landslides in these areas than would be expected from a sedimentary process with no AOC.

espanolSe ha realizado el estudio del registro sedimentario del drift con-tornitico asociado al monte submarino Villa de Djibouti (mar de Al-boran, Mediterraneo occidental) con el fin de reconstruir las areas fuente de polvo eolico desde el Pleistoceno Superior al Holoceno. Se han podido diferenciar tres end-members (EM1 grueso, EM2 limoso y EM3 fino) que caracterizan la distribucion granulometrica de las principales poblaciones de polvo eolico. Las areas fuente mas pro-bables de estas particulas son las cuencas sedimentarias y los de-siertos, asi como las cuencas cratonicas del corredor Sahara-Sahel, cuya prevalencia en el registro sedimentario experimenta un cambio durante la transicion de MIS 5 a MIS 4. Se han reconocido algunos aportes puntuales del monte coincidiendo con periodos de bajada del nivel del mar, pero no se han encontrado evidencias de aportes fluviales en los depositos contorniticos. EnglishThe sedimentary record of the contourite drift associated with the Djibouti Ville seamount (Alboran Sea, western Mediterranean) has been studied to reconstruct the source areas of the aeolian dust from Late Pleistocene to Holocene. Three end-member grain-size distributions address for different aeolian populations (coarse EM1, silty EM2 and fine EM3). For these particles, the most probable sour-ce areas are the Saharan sedimentary basins and deserts as well as the cratonic basins of the Sahara-Sahel corridor, whose prevalence in the core record changes by the MIS 5 to MIS 4 transition. Some punctual sediment inputs from the seamount have been recognized during sea-level low-stand but there is no evidence for fluvial supply in the drift deposits.

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.