SERNAGEOMIN reported that a dome-like structure was first visible on the floor of Láscar’s summit crater in 30 January satellite images, after a period of increased seismicity recorded during the previous few days. The structure was 81 m by 93 m in dimension and covered an area of about 5,332 square meters. Seismicity was low during 1-7 February, though levels increased towards the end of the week. The dome was bigger in a 2 February satellite image and covered an area of 6,290 square meters, suggesting an estimated extrusion rate of 308 square meters per day during 30 January-2 February. At 2053 on 4 February a low-level, reddish-colored gas emission rose 200-340 m above the crater rim and drifted SW. The Alert Level remained at Orange (the second highest level on a four-color scale) and SENAPRED warned the public to stay at least 10 km away from the crater. ONEMI maintained an Alert Level Yellow (the middle level on a three-color scale) for San Pedro de Atacama (70 km NW).

Geological Summary. 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.

Sources: Servicio Nacional de Geología y Minería (SERNAGEOMIN), Oficina Nacional de Emergencia-Ministerio del Interior (ONEMI)