Strong Strombolian activity that fed a tephra column 4.5 km high began at 1130 on 14 July and continued for about 3 hours. Lapilli fell S of the volcano and onto the towns of El Patrocinio (3.5 km W of the crater) and El Caracol (3 km SW). Two small lava flows were extruded, extending about 150 m to the N (roughly 200 m wide) and SW (about 10 m wide). The activity destroyed the small cone that had been growing within MacKenney Crater and ejected debris that had clogged much of its floor, leaving a significantly larger crater.

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.

Information Contacts: E. Sánchez and Otoniel Matías, INSIVUMEH.