Chillahuita is a dacitic lava dome in northern Chile. It may have formed after the Pleistocene, although Argon-argon dating on amphibole has indicated an age of 370,000 ±40,000 years. It has an altitude of about 4,750 metres (15,580 ft). It formed in a single non-explosive eruption.
The flow moved north and eastward from the vent over a terrain with slopes of 3-4°. The flow has a surface area of 11 square kilometres (4.2 sq mi) with a flat circular surface containing flow folds. Steep 200 metres (660 ft) high flanks limit the flow, which has a total volume of 4 cubic kilometres (0.96 cu mi). It is surrounded by a pumice deposit probably from the San Pedro volcano to the northwest.
The eruption of the Chillahuita dome appears to have been controlled by local fault systems associated with the Altiplano-Puna volcanic complex, which also has geochemical similarity with Chillahuita lavas.