Lucia Lobera, Pablo Gutiérrez Santolalla, Francisco 2015 2015 The objective of this report is to present a geological study of a deep-seated landslide located near the village of Arguisal (Alto Gállego, Huesca). The study area is situated in the western part of the south Pyrenees, on the Eocene Jaca-Pamplona. The most characteristic feature of the area is a 1.4 km. long and 3 km. wide rotational slide developed on Lower Eocene flysch materials. The landslide shows evidence of recent activity signs and constitutes a potential risk for human structure, including Arguisal village. The investigation includes a detailed geomorphological map, addresses the failure mechanisms, discusses the potential controlling factors and assesse the associated hazard and risk.