Report on Santa Maria (Guatemala) — 7 August-13 August 2013
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 7 August-13 August 2013
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2013. Report on Santa Maria (Guatemala). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 7 August-13 August 2013. 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 two explosions on 7 August from Santa María's Santiaguito lava-dome complex were followed by white plumes that rose 500 m. Pyroclastic material descended the E, S, and SW flanks. Fumarolic plumes rose 100 m on 8 August. On 10 August white plumes rose 250 m. An explosion at 0624 generated an ash plume that rose 900 m and drifted SW, causing ashfall in Monte Claro (S). Heavy rainfall on 11 August caused a lahar in the San Isidro-Tambor River, a tributary of Samala River, which was 30 m wide, 1.5 m thick, and carried branches, tree trunks, and blocks up to 1.5 m in diameter. A few explosions on 13 August generated ash plumes that rose 1 km and drifted 10 km WSW.
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.