The lake was formed by volcanic-tectonic phenomena; specifically, a major collapse of the Parinacota volcano dammed a former Rio Lauca, forming Chungará Lake, at some time between 8,000 and 15,000 - 17,000 years ago. This collapse involved about and covered about with debris; before the collapse took place the lakefloor of Chungará Lake consisted of alluvial and river sediments left by the Rio Lauca which drained the area. Upon damming, water from the river accumulated and formed Chungará Lake. The exact time of the collapse is controversial. Faulting also played a minor role in the formation of the lake basin, with a southwest-northeast trending fault disrupting sediments in the northwestern sector of the lake. Since the birth of Chungará Lake, about of sediment have accumulated on its floor.