Report on Santa Maria (Guatemala) — 2 March-8 March 2011
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 2 March-8 March 2011
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2011. Report on Santa Maria (Guatemala). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 2 March-8 March 2011. 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 2-3 March explosions from Santa María's Santiaguito lava dome complex produced ash plumes that rose 800 m above Caliente dome and drifted SW. Avalanches traveled S, SE, and SW, and ashfall was reported in Monte Claro, Patzulín, La Florida, and El Faro on the S and SE flanks. Two pyroclastic flows were also detected. On 3 March an explosion produced an ash plume that rose 800 m above Caliente dome and drifted W and SW. Ashfall was reported in multiple areas downwind. The explosion was accompanied by a pyroclastic flow that traveled 2.5 km down Rio Nima I on the SE flank. A few explosions occurred during 3-4 March; ash plumes rose 900 m above Caliente dome. Ash fell in La Florida, El Faro, and Palajunoj (SW flank). Based on analyses of satellite imagery, the Washington VAAC reported that ash was detected on 6 March. The next day an ash plume drifted almost 20 km SW.
During 7-8 March the seismic network detected explosions, avalanches, and pyroclastic flows. At least eight pyroclastic flows descended the E flank and deposited material in Rio Nima II. Ash plumes rose 1 km and drifted S and SW causing ashfall in areas downwind.
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.