Retrospective analysis of the Pico del Castillo de Vinuesa large historical landslide (Cordillera Iberica, Spain)

The failure mechanism of a large historical landslide that caused the partial destruction of the Pico del Castillo de Vinuesa has been determined and characterized by a multidisciplinary approach. This study combines the application of complementary fields such as geological analyses, field and laboratory tests, geomorphological, geomechanical and hydrogeological characterizations, retrospective mathematical simulations, and absolute dating methods to determine the origin and age of the landslide. The instability event occurred shortly before 1600 BP and mobilized more than 30 million m(3)of debris from the competent conglomerate layer that formed the ancient summit. The conglomerate is considered to have slid over a claystone layer dipping 12 degrees, following a translational sliding model. The underlying claystone layer constituted the impervious base of the aquifer formed by the displaced material. The hydrogeological conditions played a key role in the slide by changing the mechanical properties of both the claystone and the conglomerate layers.