ABSTRACT
Giant volcanic landslides are one of the most hazardous geological processes and present a significant danger in several volcanic areas of Europe. On Tenerife, seven large landslides affected the subaerial and submarine morphology during the last ~6 Ma. A comprehensive analysis of the La Orotava events has been carried out including site investigation, laboratory tests and stability analyses. The results revealed that the stability of the volcano can be strongly reduced by geologic, morphologic, climatic and volcanological factors. Widespread residual soils might act as potential slip surfaces, while deep erosive canyons probably evolve into the lateral limits of the failures. A high coastal cliff, humid climate and especially persistent dike intrusion have also contributed to critical stability conditions of the volcano flank. Finally, seismic ground acceleration generated by a strong and adjacent earthquake triggered the catastrophic landslides. On Tenerife, a temporal coincidence of large landslides with caldera collapse events suggests that strong earthquakes associated with caldera collapses may have triggered the failures.
