INSIVUMEH reported that eruptive activity continued at Fuego during 21-28 May. Explosions were recorded daily, averaging 1-10 per hour on most days, when counts were reported. 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 W, SW, and S. Frequent block avalanches descended various drainages including the Ceniza (SSW), Seca (W), Taniluyá (SW), and Las Lajas (SE), Honda (E), and Trinidad (S), and sometimes reached vegetated areas. Weak rumbling sounds and shock waves that rattles nearby houses and buildings were reported on most days. Ashfall was reported on almost all days in areas downwind including El Porvenir (11 km SW), El Rodeo, Finca Palo Verde, Sangre de Cristo (8 km WSW), Santa Sofía (12 km SW), Los Yucales (12 km SW), Panimaché I and II (8 km WSW), and Morelia (9 km SW), Finca La Asunción (12 km SW), La Rochela (8 km SSW), Finca Ceilán (9 km S), and San Andrés Osuna (11 km SSW). Ashfall was forecasted for areas downwind during 26-27 May. The explosions also ejected incandescent material up to 400 m above the summit on most days. Weather conditions sometimes prevented visual observations.

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)