During 16-22 July, INSIVUMEH reported moderate to strong explosions at Fuego with incandescent blocks being expelled 200-500 m above the crater. On July 22 the explosions also ejected gray ash. Most days weak avalanches moved down the flanks. Light gray eruption columns reported on 16 July rose 4-4.5 km (13,100-14,800 ft) a.s.l. and drifted 7-10 km W, SW, WSW, E, and NE. Weak white fumarolic plume rose 200-300 m above Fuego’s summit crater. A special bulletin on 18 July noted an increased number of explosions and a change in the eruptive pattern. Rumbling and jetting sounds often accompanied moderate to strong explosions that produced shock waves 12-15 km away and rattled structures in Panimache and Morelia on the flanks.

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)