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Report on Santa Maria (Guatemala) — 18 August-24 August 2021

Santa Maria

Smithsonian / US Geological Survey Weekly Volcanic Activity Report,
18 August-24 August 2021
Managing Editor: Sally Kuhn Sennert

Please cite this report as:

Global Volcanism Program, 2021. Report on Santa Maria (Guatemala). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 18 August-24 August 2021. Smithsonian Institution and US Geological Survey.

Weekly Report (18 August-24 August 2021)

Santa Maria


14.757°N, 91.552°W; summit elev. 3745 m

All times are local (unless otherwise noted)

INSIVUMEH reported that daily ash plumes from Santa Maria’s Santiaguito lava-dome complex during 18-25 August rose to 2.8-3.5 km (9,200-11,500 ft) a.s.l. and drifted as far as 8 km W and SW. Ashfall was reported in San Marcos (8 km SW), Loma Linda Palajunoj (6 km WSW), and surrounding farms on 24 August. An active lava flow 600 m long extended down the W and S flanks of the dome during 18-24 August. Collapses of blocky lava from the Caliente dome generated block-and-ash avalanches down the W, S, and SW flanks, often reaching the base and causing minor ashfall on the flanks. Weak explosions accompanied these avalanches on 21 August and generated abundant gas-and-steam emissions. Nighttime incandescence was often observed from the lava flow and dome.

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.

Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH)