INSIVUMEH and CONRED reported an increase in seismicity and in the number of explosions at Fuego on 31 October. Ash plumes during 31 October-5 November rose 1 km above the summit and drifted 15 km W and SW. Ashfall was reported in areas downwind including Morelia (9 km SW), Santa Sofia (12 km SW), Sangre de Cristo (8 km WSW), Panimaché (8 km SW), and San Pedro Yepocapa (8 km NW). By 2 November a lava flow had traveled 300 m down the Ceniza (SSW) drainage, and by 4 November lava flows 600 m long descended the Ceniza and Taniluyá (SW) drainages. Explosions on 4 November produced shock waves that rattled nearby structures, and on 5 November ejected incandescent material 200 m high. INSIVUMEH reported another increase of activity on 6 November characterized by a period of constant explosions, and ash plumes rising over 1 km and drifting 20 km W and SW. Ashfall was reported in multiple areas including Panimaché, El Porvenir, Morelia, Santa Sofia, Sangre de Cristo, Finca Palo Verde, and San Pedro Yepocapa. Incandescent material was ejected 200-300 m high and caused avalanches that reached vegetated areas in the Seca and Taniluyá drainages. A 1-km-long lava flow was active in the Ceniza drainage. Shock waves from explosions vibrated local houses.

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)