Report on Santa Maria (Guatemala) — 5 December-11 December 2012
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 5 December-11 December 2012
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2012. Report on Santa Maria (Guatemala). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 5 December-11 December 2012. Smithsonian Institution and US Geological Survey.
14.757°N, 91.552°W; summit elev. 3745 m
All times are local (unless otherwise noted)
INSIVUMEH reported that during 6-7 December incandescence from Santa María's Santiaguito lava-dome complex was visible, and an explosion generated an ash plume that rose 300 m and drifted E. During 8-11 December avalanches were produced from the fronts of lava flows on the SE, S, and SW flanks. A recent lava flow traveled 700 m down the S flank. Ash plumes that rose from the avalanches drifted 10 km W and SW. Crater incandescence was observed at night. A special bulletin on 11 December noted that a new lava flow had traveled down the N flank. Crater incandescence continued to be observed at night.
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.