The capital is Putre. It is named after the volcano Parinacota.

Putre
Putre is a city in northern Chile, in the region of Tarapacá. It is the capital of the province of Parinacota, and is 130km (78 miles) east of Arica, at an altitude of 3500 metres (11,400 feet.) Putre is on the edge of the Lauca National Park, and is popular with visitors to the National Park wishing to acclimatise to the altitude.

The Parinacota Volcano
Parinacota is a massive stratovolcano on the border of Chile and Bolivia. It is part of the Nevados de Payachata group of volcanoes. The other major edifice in that group is the Pleistocene peak of Pomerape. Parinacota's last eruptive phase has been dated using the helium surface exposure technique, which ties the eruption to 290AD ± 300 years. One of the most dramatic eruptive events in the volcano's past was 8000 years ago, when a major collapse of the edifice produced 6km3 debris avalanche. That avalanche blocked drainage patterns in some of the local area, creating Lake Chungará.