Purico is a circular shield with a diameter of , whose slopes descend away from a centre at an elevation of . This shield forms a plateau, which is known as the Chajnantor Plateau, and which contains further flat areas such as Llano de Chajnantor, Pampa El Vallecito and Pampa La Bola. There is no evidence that a caldera exists there, unlike in many other volcanoes of this type. To the west, close to the margin of the Salar de Atacama, the shield drops down to a bajada. A north-south trending system of fractures and conspicuous normal faults cuts across the western margin of the Purico complex.