Report on Santa Maria (Guatemala) — 26 November-2 December 2003
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 26 November-2 December 2003
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, 26 November-2 December 2003. Smithsonian Institution and US Geological Survey.
14.757°N, 91.552°W; summit elev. 3745 m
All times are local (unless otherwise noted)
On 28 November the Santa María seismic network recorded several explosions at Santiaguito lava dome. INSIVUMEH noted that many of the explosions were followed by block-and-ash avalanches, which traveled SW and S down Caliente cone. At least five collapses of megablocks from the S edge of the active crater generated short pyroclastic flows that descended to the base of Caliente cone. On 1 December ash emissions traveled SE and nearly constant avalanches occcurred in the active lava-flow area.
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.