Lastarria Volcano | John Seach



25.17 S, 68.50 W
summit elevation 5697 m

Lastarria Volcano is located in the Argentina/Chile border. The volcano contains five summit craters. A large avalanche deposit is located on the SE flank.

Fumaroles are located on the edges and flanks of the younger northern craters. The petrography of the Lastarria complex ranges from pyroxene andesites to pyroxeneamphibole dacites.

Geothermal activity at Lastarria volcano consists of a pressurised partially sealed system similar, but smaller to the ones observed at Yellowstone, Long Valley and Campi Flegrei.

Debris avalanche
A pre-historic collapse occurred on the southeast flank of Lastarria volcano. The debris avalanche climbed and over-rode an older scoria cone 125 m high, located due east of Lastarria, before coming to rest. The avalanche has an unusually high velocity of 300 km/hr. At Lastarria, the detached mass was fluidised and incoherent, unlike Mt St Helens, which consisted of large coherent blocks, composed of interleaved lavas and pyroclastic layers.

Sulphur Flows
Lastarria volcano is one of the few locations where sulphur flows have occurred. Sulphur usually flows as a Newtonian fluid, but the presence of gas bubble and crystals at Lastarria sulphur flows indicated it may have behaved as a Bingham fluid.

Further reading
Aguilera, Felipe, et al. "Geochemical model of a magmatic–hydrothermal system at the Lastarria volcano, northern Chile." Bulletin of volcanology 74.1 (2012): 119-134.

Naranjo, J.A. and Francis, P., 1987. High velocity debris avalanche at Lastarria volcano in the north Chilean Andes. Bulletin of Volcanology, 49(2), pp.509-514.

Naranjo, J.A., 1985. Sulphur flows at Lastarria volcano in the North Chilean Andes. Nature, 313(6005), pp.778-780.

Lastarria Volcano Eruptions

No recent eruptions.