INSIVUMEH reported that eruptive activity continued at Fuego during 13-20 August. Daily explosions were recorded by the seismic network, averaging 3-11 per hour. The explosions generated gas-and-ash plumes that rose as high as 1.1 km above the crater rim and drifted as far as 30 km NW, W, and SW. The explosions ejected incandescent material 50-300 m above the summit on most days and produced avalanches of material that descended the flanks, sometimes reaching vegetated areas. Weak rumbling sounds were reported on most days. Ashfall was reported on a few of the days in areas downwind including Panimaché I and II (8 km SW) Finca Palo Verde (10 km SW), El Porvenir (10 km S), Santa Sofia (12 km SW), Sangre de Cristo (10 km SW), Morelia (10 km SW), Los Yucales (12 km SW), Yepocápa (8 km NW), and other nearby communities. Ashfall was forecast for areas downwind on some of the other days. During the afternoon of 18 August lahars descended the Seca, Mineral, Ceniza, and Zarco drainages, carrying tree branches, trunks, and blocks as large as 1.5 m in diameter.

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)