Paul Newton and Paulino Alquijay have continued to monitor Fuego from Antigua since last October. Intermittent vapor emission from the summit and several other vents high on the flanks continued through January. Vapor occasionally rose more than 1 km above the summit, but activity was often weak and there were periods of as much as four days when no vapor emission was visible from Antigua.

The following report from William I. Rose, Jr., is based on air and ground observations between 22 January and 10 February. "Fuego was in a state of continous gas emission, mainly from vents around the edges of the summit crater. The plume varied considerably in intensity, but on its most impressive days it extended many tens of kilometers. The intense fumarolic activity at and around Fuego's summit has produced a broad white and yellow zone of encrustations above about 3,500 m elevation. The crater itself was 35 m in diameter, symmetrical, and about 20 m deep."

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: P. Newton and P. Alquijay, Antigua; W. Rose, Jr., Michigan Tech. Univ.