Update to the Map of Areas Prone to Mass Movement Phenomena in the City of Ocaña, Norte De Santander, Colombia

Abstract

Mass movement phenomena (MMP) are movements of material on slopes that can cause disasters. In Colombia, according to data from the National Planning Department, 66% of disaster-related deaths are attributed to these phenomena, which threaten nearly 11.7 million hectares. Understanding their occurrence is key to risk management. In mountainous regions such as Colombia, MMP are frequent due to topographic, climatic, and seismic conditions. In Norte de Santander, one of the country’s most exposed departments, the Geotechnical and Environmental Research Group (GIGMA) updated the map of areas prone to these phenomena in the city of Ocaña using geographic information systems. A total of 581 sites in 46 neighborhoods were evaluated, characterizing the failure mechanisms and identifying vulnerable elements. Compared to previous maps, new affected areas were identified, some of which had been classified as stable in earlier studies. The results reveal that 78% of the evaluated sites present active MMP, primarily landslides and rockfalls. The most common triggering factors are inadequate slope cuts and improper stormwater management. The Simón Bolívar neighborhood is the most affected, with 65 areas with active MMP. This updated map provides an essential tool for risk management in Ocaña, allowing for the prioritization of prevention and mitigation actions. In addition, community awareness efforts are crucial for promoting safe practices in these vulnerable areas.