Spatial and morphometric relationships of submarine landslides offshore west and southwest Iberia

Abstract

Submarine landslides are a ubiquitous geohazard in the marine environment and occur at multiple scales. Increasing efforts have been made during the last decade to catalogue and categorise submarine landslides in comprehensive databases, aiming to better understand their preconditioning and trigger factors. Using the recently compiled, open-access MAGICLAND dataset, we investigate the distribution and morphometric trends of submarine landslides observed in seven distinct geomorphologic domains offshore west and southwest Iberia. Higher densities of submarine landslides occur on the proximal regions of the south and southwestern margins of the study area. These regions are located adjacent to or coincident with higher density areas and clusters of earthquake epicentres. Submarine canyons are another major location for collapses which are particularly abundant at canyon mouths. However, significant numbers occur within all domains with pronounced relief, including distal regions hundreds of kilometres away from the foot of the continental slope. Landslide size range is inversely proportional to their spacing and frequency, a tendency observed within each domain on the whole study area. Positive correlations were obtained between the parameters analysed, but relationships between unidimensional parameters such as length and width exhibit lower correlation coefficients. Correlations between 2D and 3D parameters such as area and volume are stronger, supporting similar findings by other studies. The relationships obtained are, however, variable across domains, and the correlation values are influenced by the seafloor geomorphology. This work brings new insights on submarine landslide distribution in the understudied west and southwest Iberian continental margin, complements previous inventories made for nearby regions, and provides valuable data with wider applications for submarine landslide databases.