Report on Santa Maria (Guatemala) — February 1981
Scientific Event Alert Network Bulletin, vol. 6, no. 2 (February 1981)
Managing Editor: Lindsay McClelland.
Santa Maria (Guatemala) Ash and gas emissions; avalanching
Please cite this report as:
Global Volcanism Program, 1981. Report on Santa Maria (Guatemala). In: McClelland, L (ed.), Scientific Event Alert Network Bulletin, 6:2. Smithsonian Institution. https://doi.org/10.5479/si.GVP.SEAN198102-342030.
14.757°N, 91.552°W; summit elev. 3745 m
All times are local (unless otherwise noted)
Three geologists from Michigan Tech. Univ. spent 12 February on Santiaguito Dome. At 1410 an explosion at Caliente Vent sent up a 400-m-high vertical column of fine ash. It was the only explosion in 8 hours of observation, but two increases in the vent's vapor plume indicated additional gas emissions during that time. The vent was more active late last year when other geologists visited it.
Large dust clouds in the early morning suggested that avalanching was continuing down the SE slope of the dome. Fine ash coating the leaves and the ground was notable in the area NW of the volcano.
Geologic Background. Symmetrical, forest-covered Santa María volcano is one of the most prominent of a chain of large stratovolcanoes that rises dramatically above the Pacific coastal plain of Guatemala. The stratovolcano has a sharp-topped, conical profile that is cut on the SW flank by a 1.5-km-wide crater. The oval-shaped crater extends from just below the summit to the lower flank and was formed during a catastrophic eruption in 1902. The renowned Plinian eruption of 1902 that devastated much of SW Guatemala followed a long repose period after construction of the large basaltic-andesite stratovolcano. The massive dacitic Santiaguito lava-dome complex has been growing at the base of the 1902 crater since 1922. Compound dome growth at Santiaguito has occurred episodically from four westward-younging vents, the most recent of which is Caliente. Dome growth has been accompanied by almost continuous minor explosions, with periodic lava extrusion, larger explosions, pyroclastic flows, and lahars.
Information Contacts: W. Rose, Jr., T. Bornhorst, and C. Chesner, Michigan Tech. Univ.