Overflights of Fuego were made on 15 and 16 February by volcanologists from INSIVUMEH and Michigan Tech. The following is from their report.

"Continuous gas emission was observed, with no evidence of any magma at the surface. The geometry of the summit crater and its surroundings (which influences the paths of pyroclastic flows during eruptive activity) was unchanged since 1980. COSPEC measurements of SO₂ emission rates were made from the air, yielding 265 ± 33 t/d on 15 February and 120 ± 30 t/d on 16 February (3 and 8 determinations respectively). These rates are very similar to the 100 t/d measured in February 1980 and much less than the rates measured in February 1978 (660-1,700 t/d) when Fuego was actively erupting (Stoiber et al., 1983; reference under Santiaguito)."

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: Otoniel Matías and Rodolfo Morales, Sección de Volcanología, INSIVUMEH; W.I. Rose, Jimmy Diehl, Robert Andres, Michael Conway, and Gordon Keating, Michigan Technological Univ, USA.