INSIVUMEH reported that 1-4 weak explosions per hour were recorded at Fuego on most days during 16-23 May. The explosions generated ash plumes that rose 250-750 m above the crater; the plumes drifted S and SW during 18-20 May and as far as 10 km SW during 21-22 May. Slight incandescent at the crater was occasionally visible during dark hours a few times during the week. Very minor ashfall was reported in Morelia (9 km SW) and Panimaché (8 km SW) during 20-22 May.

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)