On 16 December INSIVUMEH reported that activity at Fuego decreased, although lava flows remained active in the Las Lajas (SE), Trinidad (S), and Santa Teresa (SW) drainages. Ash plumes from weak explosions drifted 15 km SW, S, and SE. During 16-17 December there were 4-5 explosions per hour, generating ash plumes that rose 650-750 m above the crater and drifted 8-12 km W and SW. Explosions during 20-22 December produced ash plumes that rose 550-950 m and drifted 8-10 km W. Incandescent material was ejected 150 m high, landed on the flanks, and then formed small avalanches in the Santa Teresa (SW), Taniluyá (SW), Trinidad, and Ceniza drainages.

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)