Report on Santa Maria (Guatemala) — 14 September-20 September 2011
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 14 September-20 September 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, 14 September-20 September 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 13-16 September lava flows were active on the SW and SE flanks of Santa María's Santiaguito lava dome complex. Avalanches from the lava-flow fronts also descended the flanks. Ash plumes drifted ENE. An explosion accompanied by rumbling generated an ash plume that rose 700 m above the crater and drifted SW. On 15 September a small lahar traveled down the Rio Nima II drainage. Incandescence emanated at night during 15-16 September from the lava flows and during 15-16 and 19-20 September from the crater.
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.