On 28 July CONRED noted that in recent days activity at Fuego was characterized by a high level of explosive activity. At 0545 activity increased further, heralding a shift to Strombolian activity and the beginning of the 12th eruptive episode at Fuego in 2016. Explosions produced ash plumes that rose 1 km and drifted 15 km SW, W, and NW, and caused shock waves detected in nearby areas. Pyroclastic flow descended the Las Lajas (SE) drainage, and ashfall was reported in Sangre de Cristo (8 km WSW) and San Pedro Yepocapa (8 km N). INSIVUMEH reported that during 28-29 July lava was ejected 500 m above the crater; lava flows traveled 3 km down the Santa Teresa (W) and Las Lajas drainages. Pyroclastic flows continued to descend the flanks. Ash plumes rose 1.7 km and drifted 35 km W and SW. Activity declined at 1500 on 29 July; ash plumes rose 800 m. On 30 July there were 3-5 explosions detected per hour, generating gray ash plumes that rose 550-850 m and drifted 10 km W and SW. Incandescent material was ejected as high as 150 m above the crater. Lava flows remained incandescent as far as 1.8 km in the drainages. Ash fell in Morelia (9 km SW), Santa Sofía (12 km SW), El Porvenir (8 km ENE), and Panimaché I and II (8 km SW). INSIVUMEH noted that at 0130 on 30 July the activity ended. Minor explosions generated ash plumes that did not rise higher than 750 m.

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