Lascar is the most active volcano in the Andean Central Volcanic Zone, and a steady pattern of eruptive activity has persisted for centuries. The volcano persistently features a tall plume of water and sulfur dioxide. Most present-day activity consists of the release of fumarolic gas with additional vulcanian activity that generates eruption columns several kilometres high, typically every three or two years, as well as active deformation of the three active craters observed in interferometric synthetic-aperture radar. The long-term magma supply rate of Lascar is about .