INSIVUMEH reported that on 18 April steaming hot lahars descended Fuego’s Ceniza (SSW) and Taniluyá (SW) drainages, carrying variously-sized material including blocks up to 2 m in diameter. The lahars were 1 m deep, 15 m wide, and had a sulfur odor. During 20-23 April there were 17-22 explosions per hour, generating ash plumes that rose almost as high as 1.1 km and drifted 15-20 km S, SW, and W. Shock waves vibrated local structures. Incandescent material was ejected 300-450 m high and caused avalanches of material that occasionally traveled long distances down Seca, Taniluyá, Ceniza, Trinidad, Las Lajas, and Honda ravines. A lava flow, 600 m long, advanced in the Seca drainage. Ashfall was reported in reported in Yepocapa (8 km N), Morelia (9 km SW), Santa Sofia (12 km SW), Sangre de Cristo (8 km WSW), and Panimache (8 km SW).

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)