ANáLISIS DE UMBRALES EMPíRICOS DE LLUVIA PARA EL PRONóSTICO DE MOVIMIENTOS EN MASA EN EL VALLE DE ABURRá, COLOMBIA

mass movements are the product of a progressive reduction of strength of slope geomaterials by human actions or natural processes, such as weathering, and triggered by external factors like rainfall or earthquakes. these events have demonstrated throughout history its destructive capacity, causing huge human and economic losses, especially in tropical and mountainous terrains, such as the aburrá valley. for this reason new studies on rainfall forecasting, real-time monitoring and the definition of critical rainfall thresholds have become essential tools for the implementation of early warning systems. this analysis of critical rainfall thresholds for landslides forecasting in the aburrá valley was performed by an empirical procedure, using a database of mass movements and a database of precipitation with 15-min temporal resolution. accumulated rainfall for every mass movement was estimated for short-term -la- (1, 3, 5 and 7 days) and long-term -laa- (5, 10, 15, 30, 60 and 90 days). the results show that the major determinant for the occurrence of mass movements in the aburrá valley is the laa. the data indicate that mass movements used in the analysis occurred for laa over 60 mm for 30 days, 160 mm for 60 days and 200 mm for 90 days. however, it is necessary to evaluate in detail this type of analysis and thresholds, widely performed in the world, clearly influenced, due to they generally do not consider those rainy days when there were no mass movements. therefore further studies should be carried out based on analysis of rainfall series and exceedance probabilities.