Evolución del deslizamiento de Pajonales (Depresión de Tirajana, Gran Canaria)un caso de reactivación parcial progresiva

Abstract

We have studied the evolution of the different stages of Pajonales landslide (Tirajana ravine, Gran Canaria), from the geotechnical characteristics of in situ and mobilized volcanic materials.Representative samples of pyroclasts and soils from landslides were collected and laboratory tests were performed to determine the shear strength. The morphology of slope prior to sliding was reconstructed considering the location of the failure surfaces and scarps of first and second generation. Failure surfaces for each stage of sliding were identified using a program of limit equilibrium analysis. These surfaces have been developed through clayey silt levels that result from the alteration of pyroclastic materials, showing the most unfavourable geotechnical properties (minimal or residual values).Moreover, the presence of water is a triggering factor, since total or partial saturation of the materials is required. Finally, the landslide is a progressive type: as successive reactivations occur, the sliding masses are broken down into smaller ones moving towards the Tirajana ravine.