INSIVUMEH reported that on 15 July activity at Fuego increased, characterized by eight explosions per hour detected by the seismic network and ash plumes that rose 1.1 km above the crater. Ash fell on the W and SW flanks. During 17-19 July there were 3-6 explosions per hour detected. Ash plumes rose as high as 850 m above the crater and drifted at least 12 km W and SW, causing ashfall in areas downwind including Yepocapa (8 km N), Sangre de Cristo (8 km WSW), and Panimaché I and II (8 km SW). Some explosions generated shock waves that rattled nearby homes and sounds resembling jet engines were heard every 3-8 minutes. Incandescent material was ejected 100-200 m high, and avalanches reached vegetated areas.

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.

Sources: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH), Coordinadora Nacional para la Reducción de Desastres (CONRED)