Report on Pacaya (Guatemala) — 21 April-27 April 2021
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
21 April-27 April 2021
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2021. Report on Pacaya (Guatemala). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 21 April-27 April 2021. Smithsonian Institution and US Geological Survey.
14.382°N, 90.601°W; summit elev. 2569 m
All times are local (unless otherwise noted)
INSIVUMEH reported that during 20-21 April explosions at Pacaya’s Mackenney Crater generated minor gas-and-ash plumes that rose 250 m above the summit and drifted S and SW. The lava flow on the SW flank continued to be active, though did not advance. White gas plumes were visible the next day rising as high as 200 m. On 23 April lava effusion ceased. The lava flows on the SW flank remained hot and gas plumes rose from parts of the flow; no advancement was visible through 27 April. Gray-and-white emissions were visible during 24-27 April, rising 100-200 m above the summit and dispersing S and SW. Occasional minor explosions ejected incandescent material 50-150 m high during 26-27 April.
Geological Summary. Eruptions from Pacaya, one of Guatemala's most active volcanoes, 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 ancestral Pacaya Viejo and Cerro Grande stratovolcanoes and the currently active Mackenney stratovolcano. Collapse of Pacaya Viejo between 600 and 1500 years ago produced a debris-avalanche deposit that extends 25 km onto the Pacific coastal plain and left an arcuate somma rim inside which the modern Pacaya volcano (Mackenney cone) grew. A subsidiary crater, Cerro Chino, was constructed on the NW somma rim and 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 armored the flanks of Mackenney cone, punctuated by occasional larger explosive eruptions that partially destroy the summit of the growing young stratovolcano.