Report on Fuego (Guatemala) — 16 May-22 May 2012
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 16 May-22 May 2012
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2012. Report on Fuego (Guatemala). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 16 May-22 May 2012. Smithsonian Institution and US Geological Survey.
14.473°N, 90.88°W; summit elev. 3763 m
All times are local (unless otherwise noted)
On 19 May seismicity at Fuego increased and explosions were heard at 5-10 minute intervals. A 600-m-long lava flow descended the W flank, and a 1-km-long and 20-m-wide lava flow descended the E flank, reaching the base of the volcano. Explosions ejected incandescent tephra 400 m above the crater, and produced ash plumes that rose 5 km above the crater and drifted 30 km S and SW. Coordinadora Nacional para la Reducción de Desastres (CONRED) raised the Alert Level to Orange (the second highest level on a 4-color scale). Pyroclastic flows also descended the flanks, prompting authorities to restrict passage on part of a highway. Ash plumes from the pyroclastic flows rose 3 km above the crater. Ashfall was reported in Morelia (7 km SW), Panimaché I and II (9 km SW), Sangre de Cristo (8 km WSW), and Yepocapa (8 km WNW). Thirteen people from El Porvenir in Alotenango (8 km ENE) evacuated to local shelters. Visual observations and seismicity indicated that activity decreased later that day.
On 20 May a few explosions generated ash plumes that rose 500 m above the crater and drifted 8 km SW. The next day cloud cover prevented observations; however explosions, rumbling, and degassing sounds were reported. On 22 May explosions generated ash plumes that rose as high as 1 km and drifted 10 km S and SE. Rumbling was heard and shock waves were detected. The lava flows were inactive and only incandescence from block avalanches was observed.
Geologic Background. Volcán Fuego, one of Central America's most active volcanoes, is one of three large stratovolcanoes overlooking Guatemala's former capital, Antigua. The scarp of an older edifice, Meseta, lies between 3763-m-high Fuego and its twin volcano to the north, Acatenango. 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 Acatenango. In contrast to 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.