Steam clouds containing a little ash rose about 1,000 m above the summit, beginning before dawn on 11 September. The eruption was preceded by felt earthquakes on 6 September at 2206 and 9 September at 0420 and was accompanied by harmonic tremor. On 12 September, emission of voluminous brown to black clouds was nearly continuous, frequently broken by 10-20-second intervals of quiescence. At 2130, incandescent bombs and ash were ejected. Ash emission was continuous on 13 September and harmonic tremor amplitude increased. Some ash fell on the W flank, at Yepocapa. The eruption had ended by 14 September [but see 2:10].

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.

Information Contacts: S. Bonis, IGN; R. Stoiber, Dartmouth College; D. Harlow, USGS, Menlo Park, CA; P. Newton, Antigua; D. Shackelford, CA.