Report on Santa Maria (Guatemala) — 24 March-30 March 2004
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 24 March-30 March 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, 24 March-30 March 2004. Smithsonian Institution and US Geological Survey.
14.757°N, 91.552°W; summit elev. 3745 m
All times are local (unless otherwise noted)
Weak to moderate explosions at Santa María's Santiaguito lava dome produced plumes up to 1 km above the vent. Light ashfall occurred in nearby areas on several occasions during the reporting period. On 25 March incandescent avalanches derived from the S flank of the Caliente dome flowed to the SE along various routes. Lahars descended the Nimá I river on 28 March and the Nimá I and Nimá II rivers on the evening of 29 March.
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.