On 17 December, INSIVUMEH reported that explosions from Fuego produced ash plumes that rose 300-800 m above the crater and drifted E and SE. Later that day the number of explosions increased, occurring at a rate of 12-15 per hour. Ash plumes rose 500-900 m above the crater and drifted E and NE. Ashfall was reported in Antigua Guatemala, 18 km NE, and San Juan Alotenango, 9 km ENE. On 20 December, weak explosions generated ash plumes that rose 500 m above the crater and drifted W and NW, and occasional rumbling noises.

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)