Large-scale catastrophic landslides have occurred at a number of locations in central and northern Argentina. The landslide hazard has recently been studied at one of these locations, in the vicinity of Villavil, Catamarca Province, in the Sierras Pampeanas of northwest Argentina. Villavil is a little village of ~350 inhabitants under serious risk of a landslide, which would destroy the village and surroundings. Seven large block-glide rockslides have developed in a Tertiary volcaniclastic-sedimentary sequence exposed in hogback ridges near the town. In the hogbacks, northwestward-dipping rocks have sheared across bedding and the detached slabs have moved downdip and overridden younger rocks on the lower slopes. Distal flows, resulting from the fragmentation of the slabs, have moved 1800 m into the ancient valley of Río Bolsón-Villavil. The movement of the detached slabs has been controlled by bedding and transgressive faults. These structures are already developed in the hogback behind Villavil, which at present has not undergone large displacements, suggesting that the sliding process may have begun and is in the quasistatic stage. Field evidence indicates conclusively that the movement mechanism involved frictional sliding on a basal slip surface, followed by a dynamic stage, which could have been a catastrophic event. Rockslide velocity may have exceeded 2 m/s. The transition from the quasistatic to the dynamic stage is thought to be abrupt, possibly resulting from dynamic (earthquake induced) loading. Geomorphic evidence indicates that the landslides have occurred intermittently from perhaps a few thousand years ago to 25 ka.