## 2 Geological Setting  
The study zone is located approximately 6 km north of the city of Granada (southern Spain). The landslide affects materials of the sedimentary fill of the Neogene basin of Granada, in the central sector of the Betic Cordillera (Figure 1). This area likely has the highest tectonic activity and seismicity rate in Spain.  
The sedimentary record of the basin is up to 2 km in thickness [26]. The basin fill is divided into two different sets: a lower group constituted by marine sedimentary rocks, Upper Miocene in age, and an upper one, of continental sedimentary rocks, Upper Miocene (Turolian) to Quaternary in age [27].  
Focusing on the landslide area, all geological formations cropping out in the area belong to the continental group (Figure 2). A first unit consisting of silts, sands and marks (MU unit) is found at the bottom of the stratigraphic series. This unit is more than 100 m thick and shows some transitions between silts, sands and yellowish marks. Marls are more frequent towards the western part of the landslide area, while silts are predominant to the south. This formation contains some thin layers of gypsum and/or limestone. Its age has been identified as late Miocene [28; 29]. A second unit consists of red silts, including some layers of clays, sands and highly cemented conglomerates (RSU unit). Both the MU and RSU units are parts of the same depositional environment. The MU unit constitutes the distal deposits of the alluvial fan system developed during the late Miocene in the area, while the RSU unit represents the proximal deposits of this system. Above these units, marks and lacustrine limestone (MLU unit) deposits exist (late Miocene in age). They crop out at the top of Mount Castillejo and in nearby areas (Figure 2). Finally, red clays, sands and conglomerates (recent red deposits, RRD unit) crop out widely north of the landslide area (Pliocene-Pleistocene in age).  
This landslide is approximately 2000 m long (from top to toe) with a maximum width of 600 m in its central part. Down the slope, the width of instability decreases and varies between 300 and 400 m near its toe. The landslide may be described as a complex one _sensu_ Cruden and Varnes [30], consisting of a roto-translational earth slide in the upper and middle parts of the slope, and an earth flow downslope (toe of the landslide). The slide affects most of the geological units previously described. At the head of the slide, RSU and MLU units are clearly recognizable in the scarps existing in this area. They show vertical displacement of 2 to 5 m. Several tilted blocks consisting of limestone (MLU unit) resting on red silts (RSU unit) may be found in the upper half of the slide. Due to agricultural activity, the structure of the materials is hardly recognizable in the remaining parts of the landslide. In the lower part, at the base of the slide and in the zone of earth flow, the landslide also involves the RRD unit. In some places, where small ravines have eroded the landslide mass, in situ marks (MU unit) are recognizable.  
Historical data of the landslide after the 1884 reactivation describe that large and deep ground cracks were recognizable in the middle part of the landslide, defining large, undisturbed blocks of materials that slid down slope [31]. From the base of the slide body, historical data also describe large debris (earth flow) that flowed downslope, damming the river Bermejo [20].