INSIVUMEH reported that during 17-18 July, gas plumes from Fuego rose to an altitude of 3.9 km (12,800 ft) a.s.l. and drifted SW. On 18 July, a hot lahar, 20 m wide and 1.5 m high, carried blocks 1-1.5 m in diameter to the W down the Santa Teresa ravine. On 20 July, the seismic network recorded 21 explosions. Associated ash plumes rose to altitudes of 4.1-4.7 km (13,500-15,400 ft) a.s.l. and drifted W and SW. Rumbling noises were reported.

CONRED raised the Alert Level to Yellow in surrounding communities on 22 July, based on a report from INSIVUMEH. INSIVUMEH reported that Vulcanian explosions produced ash plumes to altitudes of 4.1-5.2 km (13,500-17,100 ft) a.s.l. and expelled incandescent material 75-250 m above the crater. The explosions were accompanied by rumbling noises and shock waves that rattled ceilings and windows within a 25 km radius. Ashfall was reported from areas approximately 7-8 km to the SW, and incandescent avalanches of blocks rolled 500-800 m down the S flanks towards areas of vegetation. A new lava flow that initiated from an area 100 m below the S edge of the central crater traveled about 100 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: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH), Coordinadora Nacional para la Reducción de Desastres (CONRED)