Wikipedia
Planchón-Peteroa
Planchón-Peteroa is a complex volcano extending in a north-south direction along the border between Argentina and Chile. It consists of volcanoes of various ages with several overlapping calderas. Those include Volcán Planchón, Volcán Peteroa and Volcán Azufre.
A partial collapse of the complex about 11,500 years ago produced a major debris avalanche, which followed the course of the Teno River until reaching the Chile Central Valley.
Peteroa has a crater lake. Lagunas de Teno lies at the foot of Planchón volcano. In this area also is the Vergara International Pass.