Report on Lascar (Chile) — August 1986
Scientific Event Alert Network Bulletin, vol. 11, no. 8 (August 1986)
Managing Editor: Lindsay McClelland.
Lascar (Chile) Hypersthene andesite ashfall 350 km to the SE
Please cite this report as:
Global Volcanism Program, 1986. Report on Lascar (Chile) (McClelland, L., ed.). Scientific Event Alert Network Bulletin, 11:8. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198608-355100.
23.37°S, 67.73°W; summit elev. 5592 m
All times are local (unless otherwise noted)
Lascar erupted during the morning of 16 September. Strong winds deposited hypersthene andesite ash on the city of Salta, Argentina, 350 km SE [see also 12:4-5].
Geologic Background. Láscar is the most active volcano of the northern Chilean Andes. The andesitic-to-dacitic stratovolcano contains six overlapping summit craters. Prominent lava flows descend its NW flanks. An older, higher stratovolcano 5 km E, Volcán Aguas Calientes, displays a well-developed summit crater and a probable Holocene lava flow near its summit (de Silva and Francis, 1991). Láscar consists of two major edifices; activity began at the eastern volcano and then shifted to the western cone. The largest eruption took place about 26,500 years ago, and following the eruption of the Tumbres scoria flow about 9000 years ago, activity shifted back to the eastern edifice, where three overlapping craters were formed. Frequent small-to-moderate explosive eruptions have been recorded since the mid-19th century, along with periodic larger eruptions that produced ashfall hundreds of kilometers away. The largest historical eruption took place in 1993, producing pyroclastic flows to 8.5 km NW of the summit and ashfall in Buenos Aires.
Information Contacts: J. Viramonte, Univ Nacional de Salta, Argentina; Telam News Service, Buenos Aires.