Lautaro is the northernmost volcano of the Austral Volcanic Zone (AVZ) in the southernmost Chilean Andes, and is the closest volcano to the Chile Triple Junction plate boundary. Volcanoes of the AVZ originated from subduction of the Antarctic plate beneath the South American plate. The Catalog of Active Volcanoes of the World synonyms for Lautaro (Cerro Pirámide, Chalten, and Chaltel) are actually synonyms of the dramatic Patagonian granitic peak of Cerro Fitz Roy (Moreno 1985, pers. comm.). Glacier-covered and rising above the Southern Patagonian Ice Field, this dominantly dacitic volcano has a crater just below its summit on the NW side and a 1-km-wide crater on the NE flank. Ash deposits from eruptions were visible on aerial photos taken during several occasions during the 20th century, and older ash layers form prominent markers on outflow glaciers of the Patagonian icecap.