In a special report from 6 April INSIVUMEH reported a change in the eruptive pattern at Fuego indicated by seismic and acoustic data. Lava effused from a summit vent and traveled 400 m down the Ceniza (SSW) drainage. Avalanches of material descended the flank as far as 1 km, reaching vegetated areas. Explosions caused rumbling, shock waves, and ash plumes that rose 1.1 km above the summit. The report noted that this activity was similar to the eight-day phase during 16-24 March.

There were 5-14 explosions per hour recorded during 7-14 April, generating ash plumes that rose as high as 1.1 km above the crater rim and generally drifted 10-20 km in multiple directions. Minor ashfall was reported in several areas downwind including Santa Sofía (12 km SW), Morelia (9 km SW), Panimaché I and II (8 km SW), Quisache, and Sangre de Cristo (8 km WSW). Explosions sometimes produced shock waves that rattled houses in communities within a 25-km radius. Incandescent material was ejected 100-600 m high. Lava flows in the Ceniza drainage had variable lengths during the week, from 200 to 600 m long. Avalanches of blocks from the lava flows traveled sometimes long distances, and in some cases set fire to 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)