Report on Santa Maria (Guatemala) — 5 July-11 July 2017
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 5 July-11 July 2017
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2017. Report on Santa Maria (Guatemala). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 5 July-11 July 2017. 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 on 5 July a moderate lahar descended the Cabello de Ángel drainage, a tributary of the Nimá I river. Near the El Faro estate, the lahar was 30 m wide and 1 m deep, and carried blocks 50 cm in diameter. Weak explosions on 7 July generated white plumes that rose 700 m and drifted 2 km SE; minor ashfall was reported in the ranches of La Florida (5 km S) and Monte Claro (S). Weak avalanches of material traveled short distances down the E flank. Explosions during 10-11 July generated ash plumes that rose 600 m and drifted SW, causing some ashfall in La Florida.
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.