Report on Santa Maria (Guatemala) — 28 November-4 December 2012
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 28 November-4 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, 28 November-4 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 in a special bulletin on 28 November that collapses of the fronts of lava flows on the flanks of Santa María's Santiaguito lava-dome complex generated pyroclastic flows and ash plumes that rose 2.4 km and drifted 30 km S, SW, and W. Activity decreased during 28-29 November. During 29-30 November block avalanches were generated from the S edge of the crater. Pyroclastic flows generated ash plumes that rose 3.2 km and drifted 10-15 km SW, WSW, and W. Rumbling sounds were reported in areas 7 km away. During 1-2 December incandescent avalanches descended the SW lava dome. During 3-4 December a new lava flow in the crater was incandescent, and produced block avalanches and ash plumes which drifted 10 km W and SW.
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.