Report on Santa Maria (Guatemala) — 21 October-27 October 2015

Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 21 October-27 October 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, 21 October-27 October 2015. Smithsonian Institution and US Geological Survey.

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Santa Maria

Guatemala

14.756°N, 91.552°W; summit elev. 3772 m

All times are local (unless otherwise noted)


INSIVUMEH reported that on 21 October heavy rainfall in the area triggered steaming hot lahars which descended Santa María’s Nima I and San Isidro drainages. Both lahars carried blocks as large as 1.5 m in diameter; the Nimá I deposit was 18 m wide and 1.5 m deep. Explosions during 21-22 October generated ash plumes that rose 700 m above the crater and drifted SW, causing ashfall in El Rosario Palajunoj finca. Ash plumes from explosions drifted S and SE during 25-26 October; ashfall was reported in areas downwind.

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.

Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)