Landslide Susceptibility Models Utilising Spatial Data Analysis Techniques. A Case Study from the Lower Deba Valley, Guipuzcoa (Spain)

A quantitative methodology for landslide susceptibility zonationis described and its application to a study area in the lower part of the Deba Valley (Guipúzcoa,Spain) presented. Susceptibility models were obtained on the basis of statisticalrelationships between known mass movements and conditioning factors. A landslide rupturehypothesis was set and a digital database consisting of seventeen causal factors layers constructed.The modelling procedure was implemented utilising a GIS. The susceptibility analysis methodis based on the Favourability Functions approach, and two different mathematicalframeworks: probability theory and Zadehïs fuzzy set theory. Several landslidesusceptibility models were produced and validated using different sets of independent landslide data.The predictive capability of models was determined.