On September 5, 2019, the unstable rocky slope of Veslemannen in Romsdalen, western Norway, catastrophically collapsed after 5 years of continuous monitoring with a GBInsAR LiSAmobile system. During this period, the LiSAmobile system data showed that the rocky slope progressively weakened as precursor movements increased, particularly from 2017. The displacement measured by the LiSAmobile radar before the collapse was about 19 meters in the upper parts of the instability and 4-5 meters at the toe. Pre-collapse movements were associated with rainy precipitation events, where peak speeds occurred 2-12 hours after the heaviest rainfall. The GBInSAR LiSAmobile system allowed long-term monitoring of the phenomenon’s evolution and observed the two accelerations that occurred in the two years before the collapse, as well as tracking movements in the final stages before the collapse itself.