Abstract

Taapaca Volcanic Complex is a large dacitic volcano (35 km3) located in the western border of the active zone of the Central Andes of Northern Chile. Apart from early poorly preserved silicic andesites, Taapaca Volcanic Complex has generated remarkably similar porphyritic hornblende–biotite dacites with distinctive sanidine megacrysts for at least 1.5 Ma. The main products of the volcano are dacite lavas and domes with associated block-and-ash flow deposits. There have also been several sector collapses to generate debris avalanches, which are closely associated with volcanic blasts and episodes of dome growth. Four stages of evolution are recognized with volcanism occurring in short bursts between much longer periods of dormancy. Volcanism has built a substantial stratovolcano and has migrated 4–5 km towards the SW with time. Late Pleistocene to Holocene activity has involved at least three sector collapses of the hydrothermally altered flanks and domes. Volcanic blasts, block-and-ash flows, debris avalanches and lahars have been distributed down the southwestern flanks. These areas are the main populated part of the Chilean Altiplano and the location of the main road between Bolivia and the Pacific Ocean coast. A future eruption will threaten these areas and the regional economy.