INSIVUMEH reported that lava began to descend Fuego’s Ceniza (SSW) drainage on 19 April. The rate of effusion increased in the evening of 23 April and observatory staff saw a second lava flow in the Seca (W) drainage that was 170 m long. On 24 April satellite data confirmed thermal anomalies from both lava flows. The main part of the lava flow in the Ceniza was 200 m long, but prodced incandescent blocks from the end of the flow traveled an additional 240 m, reaching vegetated areas. Incandescent blocks from the end of the flow in the Seca drainage traveled 520 m. Explosions at the summit crater generated shock waves and ash plumes that rose almost 1.2 km above the crater. Avalanches of blocks from these explosions traveled up to 1 km down all flanks.

There were 5-12 explosions per hour recorded during 22-28 April, generating ash plumes as high as 1.1 km above the crater rim that generally drifted 10-15 km W and SW. Ashfall was reported in several areas downwind including Santa Sofía (12 km SW), Morelia (9 km SW), Panimaché I and II (8 km SW), and Sangre de Cristo (8 km WSW). The two lava flows continued to be active during 25-28 April; the flow in the Ceniza drainage did not advance past 200 m and the flow in the Seca drainage had extended to 800 m long. The ends of the lava flows continued to generate blocks 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)