INSIVUMEH reported that explosions from Fuego during 13-14 August generated ash plumes that drifted 10 km W and SW. Three lava flows were active; one of the flows traveled SW. Five explosions during 14-15 August ejected incandescent material 100 m high, and generated ash plumes that rose 300 m and drifted 6 km. Lava flows were 150 and 300 m long in the Taniluya (SW) and Ceniza (SSW) drainages, respectively. The next day explosions produced ash plumes that rose 550 m and drifted 10 km W. On 17 August 30-m-wide lahars carrying blocks traveled down the Las Lajas, Ceniza, and El Jute (SE) drainages. During 17-18 August explosions that were heard generated ash plumes that rose 200-300 m and drifted 7 km W. Lava flows in the Taniluya and Ceniza drainages were each 400 m long.

During 18-19 August the flow rate increased; the lava flows were 600 and 800 m long in the Taniluya and Ceniza drainages, respectively. Incandescent blocks from the lava-flow fronts rolled down the flanks and reached vegetated areas. Explosions during 19-20 August ejected incandescent material as high as 150 m, and generated ash plumes that rose 400 m.

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)