The research carried out within the project entitled "Integrated risk management in urban areas" had as one of its key objectives to map susceptibility to landslides, which resulted from the integration of six conditioning variables of stability. In this paper the thickness of residual soil and colluvium variable is shown. This topic represents a novel proposal to be included within the susceptibility maps as it allows mapping the areal distribution of soil thickness in situ and colluviums located on hillsides, relating it proportionally to the increase or decrease in mass movements. From this methodology, which involves the distribution of thicknesses from geostatistical processing of reliable hard data, four ranges of thicknesses were identified: Range1 (0 to 2.9 m), Range 2 (of 3 to 5.9 m), Range 3 (6 to 7.9m) and rank 4 (> 8 m).