Report on Santa Maria (Guatemala) — 29 July-4 August 2020
Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
29 July-4 August 2020
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2020. Report on Santa Maria (Guatemala). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 29 July-4 August 2020. 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 29 July-4 August explosions at Santa María's Santiaguito lava-dome complex generated ash plumes that rose 900 m above the crater and drifted as far as 1 km W and SW. Avalanches of blocks descended the SE, S, and SW flanks of Caliente cone; some reached the base of the cone and were sometimes accompanied by small pyroclastic flows. Minor ashfall was noted in areas downwind including San Marcos (10 km SW), Loma Linda (6 km WSW), and Palajunoj (18 km SSW) during 29-30 July and 2-4 August.
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.