INSIVUMEH reported that during 15-16 and 18-21 August lava flows from Fuego traveled 250-500 m down the Taniluyá drainage (SW), generating block avalanches that reached vegetated areas. On 17 August 20-m-wide lahars traveled SE down the Las Lajas and El Júte drainages, carrying blocks 1.5 m in diameter. Steam rose from the deposits in Las Lajas. Explosions were heard during 18-29 August but weather conditions prevented observations. Explosions during 19-21 August produced ash plumes that rose 100-300 m above the crater and drifted N, NW, W, and SW. Incandescent material was ejected 40-100 m above the crater at night. In a special report issued on 21 August, INSIVUMEH stated that seismicity had increased, along with degassing and rumbling sounds. Incandescent material was ejected 150 m above the crater, and lava flows traveled 500 m down the El Júte and Taniluyá drainages, generating block avalanches that reached vegetated areas.

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)