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Report on Pacaya (Guatemala) — 19 May-25 May 2021


Smithsonian Institution / US Geological Survey
Weekly Volcanic Activity Report, 19 May-25 May 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, 19 May-25 May 2021. Smithsonian Institution and US Geological Survey.

Weekly Report (19 May-25 May 2021)



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

All times are local (unless otherwise noted)

In a special 15 May bulletin INSIVUMEH noted that lava effusion at Pacaya ceased and activity instead was characterized by explosive activity at the summit crater. Ash-and-gas plumes rose 1 km and drifted downwind, causing ashfall in San Francisco de Sales, Concepción El Cedro, Aldea El Patrocinio, and San Miguel Petapa. Explosions ejected material up to 100 m above the summit. Ash plumes rose around 500 m above the summit and drifted 5-10 km N, NW, SW, and S during 18-21 and 24-25 May. Some explosions were recorded by the seismic network during 22-23 May; white-and-blue gas plumes rose 300-700 m and drifted 5 km W during 23-24 May.

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 Amatitl√°n 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.

Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)