Report on Santa Maria (Guatemala) — 21 November-27 November 2012
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 21 November-27 November 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, 21 November-27 November 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 21 November that collapses of the fronts of lava flows on the NE, SE, S, and SW flanks of Santa María's Santiaguito lava-dome complex generated pyroclastic flows and ash plumes that rose 1 km. Ash plumes drifted 15 km S and SE, producing ashfall in Las Marías, Calaguache (9 km S), and Nuevo Palmar (12 km S). During 24-27 November incandescence was observed, lava flows were active on the SW and SE flanks, and ash plumes rose 500 m and drifted 15 km SW. On 27 November pyroclastic flows traveled short distances, and generated ash plumes that rose 500 m and drifted 10 km S and SE.
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 3772-m-high stratovolcano has a sharp-topped, conical profile that is cut on the SW flank by a large, 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.