INSIVUMEH reported that during 26-27 September explosions from Fuego ejected incandescent tephra 75-150 m above the crater, and produced ash plumes that rose 500-800 m and drifted 7 km N and NW. A hot lahar descended the Ceniza drainage (SSW), carrying logs, branches, and blocks over 1.5 m in diameter. During 29 September-2 October explosions ejected incandescent tephra 200 m above the crater and produced ash plumes that rose 500-1,100 m. Shock waves were detected in areas 12-15 km away. Incandescent avalanches traveled 700 m down the flanks; during 1-2 October avalanches traveled S down the Santa Teresa drainage. Ashfall was reported at the observatory, and in Morelia (8 km SW) and Santa Sofia (12 km SE).

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)