158. Stability and Failure Mechanisms of Large Land-Slides in the Volcanic Island Flanks of the Canary Islands

The stability conditions and failure mechanisms of volcanic flanks in the Canary Islands, considering both, first generation collapses and potential future giant landslides on the islands affected by ancient collapses, as is the case of La Palma and Tenerife, have been analysed by means of numerical methods. Geometrical, geological and geomechanical models have been developed for Cumbre Vieja and El Teide volcanic edifices, on La Palma and Tenerife islands respectively. The mayor difficulties and uncertainties are associated to the large scale of the landslides, both in regard to their geological-geomechanical characterization and the preparation of the models. One of the main aspects investigated was the geomechanical characteristics of the volcanic materials, specially the submarine rock masses forming the substratum underlying the subaerial volcanic buildings. The low strength and high deformability properties of these rocks play a fundamental role on the stability of the island flanks, and they constitute the main key factors to assess the current stability conditions. Results of the stability analysis in terms of safety factor are presented for Cumbre Vieja and El Teide volcanic edifices.