INSIVUMEH reported that 1-3 weak explosions per hour were recorded at Fuego on most days during 24-30 May. The explosions generated ash plumes that rose between 450-750 m above the summit. The plumes drifted as far as 10 km SE on 26 and 30 May, 10 km SE and S on 27 May, and 6 km SE and S on 29 May. Ashfall was reported in El Zapote (10 km SSE), La Rochela (8 km SSW), and San Andrés Osuna (12 km SSW) on 26 and 30 May. Minor crater incandescence was occasionally visible during some nights and early mornings. Minor lahars descended the Ceniza drainage on 25 and 28 May and a weak-to-moderate lahar descended the Santa Teresa on 29 May. Both lahars consisted of hot volcanic material, branches, tree trunks, and volcanic blocks as large as 1.5 m in diameter.

Geological Summary. Volcán Fuego, one of Central America's most active volcanoes, is also one of three large stratovolcanoes overlooking Guatemala's former capital, Antigua. The scarp of an older edifice, Meseta, lies between Fuego and Acatenango to the north. Construction of Meseta dates back to about 230,000 years and continued until the late Pleistocene or early Holocene. Collapse of Meseta may have produced the massive Escuintla debris-avalanche deposit, which extends about 50 km onto the Pacific coastal plain. Growth of the modern Fuego volcano followed, continuing the southward migration of volcanism that began at the mostly andesitic Acatenango. Eruptions at Fuego have become more mafic with time, and most historical activity has produced basaltic rocks. Frequent vigorous historical eruptions have been recorded since the onset of the Spanish era in 1524, and have produced major ashfalls, along with occasional pyroclastic flows and lava flows.

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