The Mocoa Event on March 31 (2017): analysis of a series of mass movements in a tropical environment of the Andean-Amazonian Piedmont

On the night of March 31, 2017, a series of mass movements took place in the Mocoa Basin and devastated the northwestern part of its urban area. The mass movements were triggered by a 4-day rainfall accumulation and high rainfall intensities on the night of the event. After the trigger, about 420 mass movements transported material as landslides, debris flows, and hyperconcentrated flows along the Taruquita and Taruca creeks and Sangoyaco River on the northern side, and as landslides and mudflows along the Mulato River on its southern side, resulting in major damages to both its population and infrastructure. Previous reports by Cheng et al. (2018) and García-Delgado et al. (2019) described the event from a hydrological and geological perspective, connecting them with the damage caused by the event, but leaving aside an analysis of the series of mass movements and its characteristics. This work presents an extended review of these mass movements and studies them via a statistical analysis, providing a detailed review of the event’s characteristics and their relationship with the resultant damage. These characteristics are compared with the existing hazard maps and they provide valuable information and awareness on hazard management for communities settled in the northern Andes.