Report on Fuego (Guatemala) — February 1979
Scientific Event Alert Network Bulletin, vol. 4, no. 2 (February 1979)
Managing Editor: David Squires.
Fuego (Guatemala) More block lava down the E flank
Please cite this report as:
Global Volcanism Program, 1979. Report on Fuego (Guatemala). In: Squires, D. (ed.), Scientific Event Alert Network Bulletin, 4:2. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN197902-342090.
14.473°N, 90.88°W; summit elev. 3763 m
All times are local (unless otherwise noted)
After considerable lava extrusion and ash emission in early to mid-January, Fuego's activity was confined to weak steaming between 24 January and 7 February. Clouds obscured the volcano 22-23 January and from 8 February until sunset the next day.
Renewed visibility late on 9 February revealed red to bright orange-yellow block lava flowing down Barranca Honda, a canyon on the E flank. Large blocks bouncing from wall to wall of the canyon could be seen from Antigua. The next morning, dense black ash clouds were ejected, obscuring the summit area, and white vapor clouds reached a height of 2.5-3 km above the summit. By nightfall, black ash emitted from two vents formed a thin column about 1 km high and white vapor moved upwards about an additional 1.3 km. Bursts of incandescent material were thrown more than 200 m above these 2 vents. A large amount of block lava flowed down Barranca Honda, but blocks did not bounce out of the flow as they had the previous night. Lava also flowed into a second canyon N of Barranca Honda. Later in the evening, less lava was moving down Barranca Honda, but large numbers of incandescent blocks were thrown onto the N shoulder, then disappeared from view down the W flank (not visible from Antigua).
Clouds prevented night observations 11-18 February, and no lava was seen in Barranca Honda in the daytime during this period. However, ash emission continued, reaching a maximum observed height of 1.5 km and frequently rising about 1 km. Eruption clouds decreased in height and their ash contents declined 16-17 February, and no ash rose above low summit-area weather clouds on the 18th.
About midday on 19 February, block lava could again be seen flowing down Barranca Honda, and low clouds of black ash were ejected from the vents. After dark, several streams of lava were visible, flowing down Barranca Honda, a canyon to the N, and an open area on the NE flank. Glowing blocks tumbled away from the flows. On 20 February, the last day of observations reported here, lava extrusion persisted and dense black ash clouds rose about 0.5 km.
No earthquakes were felt in Antigua during the observation period, but persons nearer the volcano felt some shocks and heard numerous rumblings.
Geologic Background. 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, Antigua; UPI.