Report on Santa Maria (Guatemala) — 31 December-6 January 2004
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 31 December-6 January 2004
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2003. Report on Santa Maria (Guatemala). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 31 December-6 January 2004. Smithsonian Institution and US Geological Survey.
14.757°N, 91.552°W; summit elev. 3745 m
All times are local (unless otherwise noted)
According to seismic data, during 1-5 January weak-to-moderate explosions occurred from Santa María's Santiaguito lava-dome complex. The explosions caused block-and-ash avalanches to travel 100-250 m down the volcano's SW and S flanks and down Caliente cone. Small amounts of ash fell around the volcano, including in Monte Bellow, La Florida, and El Faro ranches (locally termed fincas).
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 stratovolcano has a sharp-topped, conical profile that is cut on the SW flank by a 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.