INSIVUMEH reported that 3-13 explosions per hour were recorded at Fuego during 14-21 December, generating ash plumes as high as 1.1 km above the crater rim and periodic shock waves that were felt in communities around the volcano. Ash plumes drifted as far as 40 km NW, W, SW, and SE; ashfall was reported in areas downwind, including Morelia (9 km SW), Panimaché I and II (8 km SW), Santa Sofía (12 km SW), El Porvenir (8 km ENE), San Pedro Yepocapa (8 km NW), Sangre de Cristo (8 km WSW), finca Palo Verde, Santa Sofía (12 km SW), and Yucales (12 km SW) during 16-18 and 20-21 December. Block avalanches descended the Ceniza (SSW), Seca (W), Trinidad (S), Taniluyá (SW), and Las Lajas (SE) drainages, often reaching vegetated areas. Explosions ejected incandescent material up to 100-300 m above the summit during 14-15 and 17-19 December. Winds lifted “curtains” of ash around the volcano during 18-19 December, and crater incandescence was visible overnight during 20-21 December.

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)