Report on Lascar (Chile) — 12 April-18 April 2006
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 12 April-18 April 2006
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2006. Report on Lascar (Chile). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 12 April-18 April 2006. Smithsonian Institution and US Geological Survey.
23.37°S, 67.73°W; summit elev. 5592 m
All times are local (unless otherwise noted)
ONEMI reported that two explosive eruptions occurred at Lascar on 18 April. The first ash emission began at 1120 and the second began at 1315. According to the Buenos Aires VAAC, a significant meteorological forecast (SIGMET) was issued for Lascar on 18 April stating that a "smoke" column was at a height of 8 km (26,250 ft) a.s.l. and was drifting eastward towards Argentina. The Aviation Color Code was at Red, the highest level. Activity ended later that day, so the Aviation Color Code was reduced to Green. The Villarrica Volcano Visual Observation Project (POVI) website reported that a cloud rose to 3 km above the volcano (28,200 ft a.s.l.), no seismic activity was recorded in the area, and no evacuations occurred.
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.