Deep mass movements susceptibility model in Asturias (North of Spain)

Abstract

A deep mass movement susceptibility model has been carried out for a 10,000 km2 sector on the northern side of the Cantabrian Mountains (northwest Spain). The input data include a 1:25.000 scale cartography of these slope instabilities (4,500 polygons), a bedrock lithological cartography at the same scale and a small watersheds subdivision. The territory has been classified into Unique Condition Units taking into account two conditioning factors: 1) bedrock lithology and 2) watershed subdivision. Following an analysis of conditional probability, the model, with continuous values of probability, has been reclassified in a map with 5 intervals of relative susceptibility. The distribution of areas with different susceptibility depends mostly on lithology, although it also shows the influence of other local factors, like relief and geomorphic situation. Some of the characteristics of the mass movements analyzed, such as the age of many of the forms and their ongoing activity, suggest that the meaning and possible applications of the susceptibility model should be considered carefully.