Report on Santa Maria (Guatemala) — 21 October-27 October 2009
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 21 October-27 October 2009
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2009. Report on Santa Maria (Guatemala). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 21 October-27 October 2009. Smithsonian Institution and US Geological Survey.
14.757°N, 91.552°W; summit elev. 3745 m
All times are local (unless otherwise noted)
Based on analyses of satellite imagery, the Washington VAAC reported that on 22 October multiple ash plumes from Santa María's Santiaguito lava dome complex drifted less than 20 km SW. On 23 and 26 October, INSIVUMEH reported that explosions produced ash plumes that rose above Caliente dome to altitudes of 3-3.3 km (10,000-10,800 ft) a.s.l. The plumes drifted W and SE and caused ashfall in areas downwind. Avalanches descended the SW flank of the dome. Degassing sounds resembling airplane engines were heard.
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.