Report on Santa Maria (Guatemala) — 24 August-30 August 2016
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 24 August-30 August 2016
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2016. Report on Santa Maria (Guatemala). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 24 August-30 August 2016. 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 at 0858 on 28 August a strong Vulcanian explosion at Santa María’s Santiaguito lava-dome complex generated a dense ash plume that rose 2.5 km and drifted 100 km W and SW. Pyroclastic flows descended the flanks. Ashfall was reported in San Marcos (10 km SW), Loma Linda (6 km WSW), and Palajunoj (18 km SSW), and was expected to impact additional areas downwind as the plume continued to drift. Moderate explosions were detected later that day. On 29 August a 25-m-wide, 1.5-m-deep hot lahar triggered by rainfall descended the Cabello de Ángel drainage, a tributary of the Nimá I river drainage on the S flank, carrying tree trunks and blocks up to 1.5 m in diameter. The lahar had a strong sulfur odor. White-and-blue gas emissions were observed on 30 August.
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.