The appearance of Corral de Coquena is similar to a maar. Despite the arid climate in the area which has persisted since the Miocene, the local water table ( beneath the ground on the basis of water levels in nearby lakes) may have been high enough to trigger phreatomagmatic activity. This activity formed the crater. Later, lava itself erupted in the form of lava fountaining. Spatters formed by the fountaining then formed the Corral de Coquena rampart.: This is an unusual mode of activity for silicic magmas but also documented at Huaynaputina and the Cerro Chascon-Runtu Jarita complex.: