An analysis of the rainfall conditions and the influence of the infiltration processes on the slope stability are important in tropical mountain terrains due to the wide occurrence of rainfall-induced landslides. Distributed physical-based models can be coupled with techniques that relate the factor of safety with rainfall thresholds associated with the occurrence of this phenomenon. This study presents a methodology that determines the thresholds of rainfall intensity and duration, for the prediction of shallow landslides, using a distributed physical model called TRIGRS. In the analysis, it is used a percentage of the critical area of failure defined for a study area. The conditions of mean intensity and duration of rain that induce this failing area to be reached are adjusted to a potential equation, within certain ranges of duration and intensity. The model is used in a sub-basin of the Valle de Aburrá (Colombia) and the results are compared with rainfall thresholds defined with another distributed physical model. The obtained results reaffirm that the conditions of rainfall intensity and duration that trigger landslides in a region exhibit scaling properties determined by relationships of potential equations, like those obtained by other researchers in different places of the world.