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Report on Pacaya (Guatemala) — 6 January-12 January 2021


Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 6 January-12 January 2021
Managing Editor: Sally Sennert.

Please cite this report as:

Global Volcanism Program, 2021. Report on Pacaya (Guatemala) (Sennert, S, ed.). Weekly Volcanic Activity Report, 6 January-12 January 2021. Smithsonian Institution and US Geological Survey.

Weekly Report (6 January-12 January 2021)



14.382°N, 90.601°W; summit elev. 2569 m

All times are local (unless otherwise noted)

INSIVUMEH reported that the lava flow that began on 2 January from a vent on the SW flank, 200 m below Pacaya’s Mackenney Crater, formed 3-4 branches and was 400 m long by 6 January. Avalanches of material descended the W, SW, and S flanks. Strombolian explosions produced ash plumes that rose 100-150 m above the cone and drifted 10 km S and SW. Explosions on 7 January produced ash plumes that rose 300-500 m above the crater and ejected ballistics 300 m away from the crater. Explosions rattled structures in nearby villages. Two new lava flows emerged on the N flank at 0740; one traveled 50 m and the other 200 m. Active lava flows on the W and SW flanks were 550 m long. Overnight during 7-8 January a new lava flow on the SW flank descended 425 m. During 9-12 January Strombolian explosions continued to ejected material up to 300 m above the cone. The lava flow on the SW flank reached a length of 1.2 km on 9 January and 1.5 km by 10 January; it remained active through 12 January. Ash plumes drifted 10 km W during 10-11 January, and avalanches form the crater area descended the SW and S flanks.

Geological Summary. Eruptions from Pacaya are frequently visible from Guatemala City, the nation's capital. This complex basaltic volcano was constructed just outside the southern topographic rim of the 14 x 16 km Pleistocene Amatitlán caldera. A cluster of dacitic lava domes occupies the southern caldera floor. The post-caldera Pacaya massif includes the older Pacaya Viejo and Cerro Grande stratovolcanoes and the currently active Mackenney stratovolcano. Collapse of Pacaya Viejo between 600 and 1,500 years ago produced a debris-avalanche deposit that extends 25 km onto the Pacific coastal plain and left an arcuate scarp inside which the modern Pacaya volcano (Mackenney cone) grew. The NW-flank Cerro Chino crater was last active in the 19th century. During the past several decades, activity has consisted of frequent Strombolian eruptions with intermittent lava flow extrusion that has partially filled in the caldera moat and covered the flanks of Mackenney cone, punctuated by occasional larger explosive eruptions that partially destroy the summit.

Sources: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH), Coordinadora Nacional para la Reducción de Desastres (CONRED)