One of the most significant processes in soil dynamics is liquefaction. It is a loss of strength coupled by a quick increase in pore pressure, causing soil particles to break apart for a brief period. There have been several approaches published for calculating the residual or liquefied shear strength of cohesionless soils. This article gives cone penetration test relationships for assessing vulnerability to loss of strength and liquefied shear strength in a variety of soils. Then, based on the results of our studies, we were able to map the liquefiable zones of the Mnasra region, located in the Gharb basin and extending over an area of 4000 km2, which is characterized by two main facies: (i) a predominantly gravelly and/or conglomeratic facies, separated by silt-clay levels (east of the nappe), (ii) a predominantly sandy, sandstone and calcareous facies, separated by silt-clay levels (coastal zone and southern sector on the Maâmora side). IPL calculations predict a spatial-temporal variation in liquefaction at depths ranging from a low probability of liquefaction to a certainty.