Gas Fluxes

SO2 emission record for Fuego (Andres et al., 1993).
Fuego is a basaltic volcano currently in repose. The SO2 emission rate measurements are consistent with a high level magma body that is crystallizing and releasing volatiles. Fuego has occasionally exhibited the presence of magma-air interfaces through which gas passes, as is typical of open vent volcanoes.

Fuego erupts high-Al, olivine basalts, and has frequent explosive eruptions (.60 since 1540) of short duration (Martin and Rose, 1981). After the 1974 eruption, Fuego was sporadically active for several years with small ash eruptions. Since 1979, it has been in repose. Rose et al. (1978) suggest that there is a magma body (>0.1 km³) 3-8 km below the summit of Fuego. Microprobe analyses indicate the pre-eruptive S content of parental Fuego magma is 2800 ppm S and post-eruptive lavas average 75 ppm S (Rose et al., 1982).

Aerial view of Fuego (left) and Acatenango (right), viewed from the SE. Note the gas fumes from Fuego's summit and the discolored fumarolic deposits. The barrancas descending the cone channel are the block and ash flows that are the earmark of Fuego's activity. Photo by Bill Rose, 19xx.

Close-up aerial view of actively fuming crater of Fuego. View is directly from the south, with Acatenango in the background. Photo by Bill Rose, 1980.

Fuego was measured from a ground-based tripod survey point during a two-month period before and after its great 1974 eruption (Crafford, 1975). Since 1974, it has been measured only during aircraft surveys. Individual SO2 measurement range from 70 to 3300 Mg/d. Considering that the higher measurements are representative of periods with fresh lava exposed at the surface and that these periods have only occurred a few times over the last 20 years, the daily 20 year SO2 emission rate for Fuego is between 100 and 700 Mg/d.

SO2-activity plots for Fuego. SO2 averages (solid) and ranges (stippled) are shown. The occurrence of various styles of activity are portrayed by the corresponding activity bars. (Andres et al., 1993).

(Andres et al., 1993)