The volcano sits above a major local geological trend, the north-south Miscanti Line. Other volcanic centres are also located on this line, including the Corona and Saltar lava domes, and the Miscanti and Lejia volcanoes. The Miscanti Line dissects the Quaternary basement beneath Lascar, and it may be a hinge of a fold that is being propagated by faults. The formation of the first cone at Lascar may have been facilitated by the intersection between the Miscanti Line and another east-west lineament formed by Pliocene-Pleistocene tectonic compression of the region, and the lineament would have worked as an ascent path for magma. At least four alignments of volcanoes are recognized in the region.