Old and recent landslides of the Barranco de Tirajana basin, Gran Canaria, Spain

The head of the Barranco de Tirajana (BdT), on Gran Canaria island (Spain) is a large natural depression that occupies 35 km(2). Its origin and evolution is due to the activity of large landslides which have been occurring since the Quaternary until the present. The bottom of the BdT basin is occupied by a complex group of slide bodies, formally named g.s.d. (gravitational slide deposits) Fm. The boundary between the g.s.d. and bedrock formations, as well as among 28 different landslides, has been established. The movements were mainly translational-type, some of them of extraordinary dimensions. Although most of the slides took place in past ages and are now stable, some of them are still active, like Rosiana landslide, affecting an arterial road and many buildings.