Abstract 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 m 3 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.

Abstract This paper presents a Geographic Information System catalogue of the submarine landslides of the Spanish continental margin and describes the problems associated with harmonizing the catalogue with its onshore homologue. The data model structure is described to explain how to apply the rules and specifications following the Infrastructure for Spatial Information in Europe (INSPIRE). Because of the singularities of the marine environment compared with those of land, integrating the submarine landslide catalogues into INSPIRE specifications requires the following procedures: (1) simplification of the list of values of state of activity into three categories: active, dormant and relict; and (2) inclusion of debris avalanches and turbidites as new typologies of landslides. This paper discusses the problems associated with harmonizing different data types and units from different sources, such as the thickness (metres and seismic two travel time) or the age of the event, and a numeric code for the geological timescale is proposed to harmonize these data. We establish whether an item is required based on the reliability of the landslide event, which is categorized by three levels (high–middle–low) depending on the precision of the data source, methodology used and quality of the publication where the data are obtained.