Report on Santa Maria (Guatemala) — 26 June-2 July 2019
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 26 June-2 July 2019
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2019. Report on Santa Maria (Guatemala). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 26 June-2 July 2019. 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 increased activity at Santa María's Santiaguito lava-dome complex in a special bulletin posted on 2 July. They note that during the previous two years activity was characterized as low, with 10-15 weak explosions per day, and emissions composed mainly of water vapor with minor ash content. Beginning on 28 June the seismic network recorded a gradual increase of the number and intensity of explosions, with 35-40 events per day. These explosions were weak-to-moderate intensity and produced ash plumes that rose 1-1.3 km above the complex and drifted S and SW. Ashfall was recorded in areas downwind including Patzulín, El Faro, Horizontes, Las Marías, Loma Linda, and San Marcos Palajunoj. Block avalanches descended the SE, S, and SW flanks and sometimes generated ash plumes.
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.