Report on Santa Maria (Guatemala) — 23 September-29 September 2015
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 23 September-29 September 2015
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2015. Report on Santa Maria (Guatemala). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 23 September-29 September 2015. 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 Observatorio del volcán Santiaguito (OVSAN) observations, INSIVUMEH reported that on 29 September explosions from Santa María's Santiaguito lava-dome complex generated multiple small pyroclastic flows. The largest pyroclastic flow traveled 4 km E down the Ángel and Nimá I drainages. Dense ash plumes drifted E causing ashfall in areas between Quetzaltenango (18 km WNW) and El Palmar (12 km S).
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.