Report on Pacaya (Guatemala) — May 1987
Scientific Event Alert Network Bulletin, vol. 12, no. 5 (May 1987)
Managing Editor: Lindsay McClelland.
Pacaya (Guatemala) Strong ash emission; lava flows; 600 evacuated
Please cite this report as:
Global Volcanism Program, 1987. Report on Pacaya (Guatemala). In: McClelland, L. (ed.), Scientific Event Alert Network Bulletin, 12:5. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198705-342110.
14.382°N, 90.601°W; summit elev. 2569 m
All times are local (unless otherwise noted)
Beginning 30 May, Strombolian eruptions ejected ash clouds from MacKenney Crater [see also BGVN 12:07]. Explosions occurred twice/minute and were accompanied by rumbling. Lava flows were observed on the N flank.
After about 3 hours of increasingly vigorous harmonic tremor, a strong eruption occurred on 14 June at 1930. At El Caracol, 3 km SW of the crater, 10 cm of ash fell in 3 hours, collapsing the roofs of two houses. About 600 residents were evacuated. Lava flowed SW and was continuing to advance two days later. As of 16 June, an ash column rose 2-3 km above the crater and tremor of 15 mm amplitude was continuing.
Geologic Background. 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.
Information Contacts: E. Sánchez, Edgar Quevec, and Enrique Molina, INSIVUMEH; Norman Banks, USGS.