On 2 September INSIVUMEH seismically detected a lahar flowing through Fuego’s Taniluyá drainage (SW flank). Observations determined a width of 75 m and height of 2.5 m. The flow cut the road between Santa Lucia Cotzulmaguapa and the communities of Morelia, Santa Sofía, and Panimaché I and II. Lahars were also detected within Río Ceniza (SSW) and Santa Teresa (W).

During 3-9 September INSIVUMEH reported that white fumarolic plumes rose 300-600 m above Fuego’s summit. Weak-to-moderate ash explosions occurred each day and generated plumes 500-800 m high; ash plumes drifted up to 15 km away with prevailing winds. Moderate rumbling was heard and shockwaves caused roofs to shake on some houses near the volcano. On 3 and 5-9 September incandescent plumes were observed 75-150 m above the crater. Weak avalanches were channeled into the drainages of Ceniza (SSW), Trinidad (S), Taniluyá (SW), Santa Teresa, Las Lajas, and Honda during 9 September.

During 3-4 and 6-9 September fine gray ash from explosions fell over the areas of Yepocapa (8 km WNW), Sangre de Cristo (8 km WSW), Panimaché I and II (8 km SW), Morelia (10 km SW), Santa Sofía (12 km SW), Yucales (12 km SW), Porvenir (8 km ENE), and others.

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)