Report on Santa Maria (Guatemala) — 20 October-26 October 2004
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 20 October-26 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, 20 October-26 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 21-22 October, weak-to-moderate explosions occurred at Santa María's Santiaguito lava-dome complex. Some explosions were followed by collapses of the SW edge of the lava dome in the crater of Caliente Dome. On 22 October two pyroclastic flows traveled down the volcano's flank. The Washington VAAC reported that hot spots and plumes possibly containing ash were occasionally visible on satellite imagery on 21 October.
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.