J. Mt. Sci. (2020) 17(5): 1161-1171 e-mail: jms@imde.ac.cn http://jms.imde.ac.cn https://doi.org/10.1007/s11629-019-5629-y 1161 Abstract: In the warm summer of 2017, a landslide failed from the south-east side of the Col des Clochettes on the top of the underlying Trajo Glacier. The study area is at an elevation of about 3500 m a.s.l. in the Gran Paradiso Massif and can be hardly reached by walking from Cogne (Aosta Valley, NW Italy). Studies conducted by field surveys, photogrammetry (structure from motion) and satellite images analysis, integrated with the evaluation of data from meteorological stations have been used to reconstruct the phenomenon and infer its causes. The site is very complex to be studied especially due to logistic problems, therefore, measurements and observations that are common practice in other landslides are very difficult to apply here. So, many of the results achieved are not adequately supported by field studies. Anyway, the following factors could have affected the stability of the slope: i) the tectonic structure of the area, which is reflected on the morphology and on the geomechanics characteristics of the rock masses; ii) the meteorological conditions during 3 months before the main failure, resulting in an extremely high temperature compared to historical data. Moreover, the analysis of multitemporal satellite images allowed to recognize that it was not a single landslide but that the phenomenon is articulated over time in at least five failures in about 2 months. Moreover, several predisposing factors may have been playing an important role in causing the instability: the degradation of permafrost (probably affecting rock mass due to the circulation of warm air and water in the discontinuity systems), the alternance of the freeze-thaw cycles and the availability of a considerable amount of water from rainfalls and nival fusion infiltrating deeply in the rock mass. More common causes such as rains and earthquakes have been excluded. Keywords: Landslide; Glacier; Remote sensing; Climate changes; Western Italian Alps Landslide on glaciers: an example from Western Alps (Cogne - Italy) FRASCA Marco 1 https://orcid.org/0000-0002-6466-600X; e-mail: marcofrasca@hotmail.it VACHA Damiano 2 * https://orcid.org/ 0000-0001-9290-5912; e-mail: damiano.vacha@unito.it CHICCO Jessica 2 https://orcid.org/0000-0001-6877-5425; e-mail: jessica.chicco@unito.it TROILO Fabrizio 1 https://orcid.org/0000-0002-6386-3335; e-mail: ftroilo@fondms.org BERTOLO Davide 3 https://orcid.org/ 0000-0001-6860-2962; e-mail: d.bertolo@regione.vda.it *Corresponding author 1 Fondazione Montagna Sicura, Località Villard de la Palud 1, 11013 Courmayeur, Aosta, Italy 2 Università degli Studi di Torino, Department of Earth Sciences, Via Valperga Caluso 35, 10125 Torino, Italy 3 Regione Autonoma Valle d'Aosta - Assessorato alle opere pubbliche, territorio ed edilizia residenziale pubblica, Località Amérique, n. 33, 11020 Quart, Aosta, Italy Citation: Frasca M, Vacha D, Chicco J, et al. (2020) Landslide on glaciers: an example from Western Alps (Cogne - Italy). Journal of Mountain Science 17(5). https://doi.org/10.1007/s11629-019-5629-y © Science Press, Institute of Mountain Hazards and Environment, CAS and Springer-Verlag GmbH Germany, part of Springer Nature 2020 Received: 1 3-Jun-201 9 1 st Revision: 17-Jul-2019 2 nd Revision: 19-Dec-2019 Accepted: 01-Mar -2020