Report on Santa Maria (Guatemala) — 13 October-19 October 2004
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 13 October-19 October 2004
Managing Editor: Gari Mayberry
Please cite this report as:
Global Volcanism Program, 2004. Report on Santa Maria (Guatemala). In: Mayberry, G (ed.), Weekly Volcanic Activity Report, 13 October-19 October 2004. Smithsonian Institution and US Geological Survey.
14.757°N, 91.552°W; summit elev. 3745 m
All times are local (unless otherwise noted)
During 14-18 October, weak-to-moderate explosions at Santa María's Santiaguito lava-dome complex produced plumes to a height of ~9 km above the volcano. Small lahars traveled down San Isidro Ravine on 14 and 15 October. A small collapse of the SW edge of the lava dome in the crater of Caliente Dome produced a pyroclastic flow on 17 October at 0749. The pyroclastic flow traveled down the S flank and produced a steam-and-ash plume to a height of ~800 m above the surface upon contact with dammed water. INSIVUMEH reported that this collapse, like those that occurred on previous days and weeks, was associated with a new cycle of magmatic refeeding and a new lava flow towards the SW flank could be emitted in the next weeks or months.
Geologic Background. Symmetrical, forest-covered Santa María volcano is part of a chain of large stratovolcanoes that rise above the Pacific coastal plain of Guatemala. The sharp-topped, conical profile 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 vents, with activity progressing W towards the most recent, Caliente. Dome growth has been accompanied by almost continuous minor explosions, with periodic lava extrusion, larger explosions, pyroclastic flows, and lahars.