In Switzerland, the canton of Valais is one of the cantons most affected by natural hazards such as debris flows, landslides or rockslides. In January 2018, a landslide of about 5000m3 occurred at the Col de la Forclaz, more precisely on the Bal du For. Numerous damages resulted, including the blocking of the main road for several days leading directly to the small village of Trient, as well as the French village of Chamonix. In order to protect the area as much as possible, several measures were taken to reduce the risk of another potential landslide. This work highlights the various elements of answers related to this rockfall. Thus, during the summer of 2021, a field campaign was conducted in the area in question in order to understand the various possible causes of the rockfall. Several drone flights have also been carried out in the area, which made it possible to obtain digital terrain models (DTMs) that will later be used to determine the trajectory of the blocks during the landslide.