Report on Santa Maria (Guatemala) — 25 July-31 July 2012
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
25 July-31 July 2012
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2012. Report on Santa Maria (Guatemala). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 25 July-31 July 2012. Smithsonian Institution and US Geological Survey.
14.757°N, 91.552°W; summit elev. 3745 m
All times are local (unless otherwise noted)
INSIVUMEH reported that during 26-27 July an explosion from Santa María's Santiaguito lava-dome complex produced an ash plume that rose 400 m above Caliente dome. White gas plumes rose 200 m and drifted SW; incandescence from the crater was reflected in the plume. On 29 July pyroclastic flows descended the S flank and generated ash plumes that rose 1.5 km above the crater and drifted 15 km SW. The next day explosions produced ash plumes that rose 1.5 km and drifted 12 km WSW. During 30-31 July explosions produced ash plumes that rose 1.5 km above Caliente dome and drifted 12 km WSW. Block avalanches on the S flank generated pyroclastic flows that traveled to the base of the volcano.
Geological Summary. 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.