Report on Santa Maria (Guatemala) — 23 May-29 May 2012
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 23 May-29 May 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, 23 May-29 May 2012. Smithsonian Institution and US Geological Survey.
14.756°N, 91.552°W; summit elev. 3772 m
All times are local (unless otherwise noted)
INSIVUMEH reported that during 22-23 and 28-29 May explosions from Santa María's Santiaguito lava-dome complex produced ash plumes that rose 400-900 m above Caliente dome and drifted E, SE, and S. During 26-27 May explosions produced ash plumes that drifted W. Avalanches were generated by the W part of the lava dome and from lava flows. On 29 May lahars traveled S down the Rio Nima I and San Isidro drainages, carrying tree branches and blocks 1-1.5 m in diameter.
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.