In a special bulletin on 13 September, INSIVUMEH reported that activity at Fuego increased, starting the sixth eruption in 2012. Lava flows traveled 600 m down the Taniluyá drainage (SSW) and the Las Lajas drainage (SE), producing block avalanches that reached vegetated areas. Strombolian explosions generated ash plumes that rose 3 km above the crater and drifted SW and 12 km W. Ash fell in multiple areas, including the villages of Panimaché (8 km SW), Morelia (8 km SW), Santa Sofia (12 km SE), Sangre de Cristo (8 km WSW), Palo Verde, San Pedro Yepocapa (8 km NW), Santiago Atitlan (42 km NW), San Lucas Toliman (32 km NW), Mazatenango (68 km W), Suchitepéquez, Retalhuleu (86 km W), and Santa Lucia Cotzumalguapa (23 km SW). Explosions produced degassing sounds and rumbling noises, accompanied by shock waves that vibrated structures on the SW flank. Pyroclastic flows traveled down the Las Lajas and Ceniza (SSW) drainages, producing ash plumes. CONRED increased the Alert Level to Orange (third highest on a four-color scale). About 10,600 people evacuated from nearby communities including Yepocapa, San Juan Alotenango (9 km ENE), Sacatepéquez. Evacuation shelters were set up in Santa Lucia Cotzumalguapa.

Later that day seismicity decreased, ash plumes rose 300 m above the crater and drifted W and NW, fewer pyroclastic flows were observed, and the rate of explosions slowed. Ashfall was reported in Panimaché, Morelia, and Sangre de Cristo. Lava flows in the Ceniza drainage were 1 km long and 150 m wide, and in Las Lajas were 700 m long and 100 m wide. CONRED noted that residents began to return to their homes on 14 September.

During 14-18 September explosions generated rumbling noises; ash plumes that rose 400-900 m above the crater drifted 7-8 km W and SW, causing ashfall in Sangre de Cristo, Panimaché I, and Panimaché II. Lava flows were at most 1.2 km long in the Taniluyá drainage and 200 m long in the Ceniza drainage during 14-16 September; flows were not observed during 17-18 September.

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)