Report on Santa Maria (Guatemala) — 22 October-28 October 2014
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 22 October-28 October 2014
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2014. Report on Santa Maria (Guatemala). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 22 October-28 October 2014. 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 22-23 October avalanches originated from the lava-flow front active on the S flank of Santa María's Santiaguito lava-dome complex. Phreatic explosions occurred at the middle and lower parts of the lava flow. On 24 October a lahar descended the San Isidro (SW) drainage, a tributary of the Tambor River, carrying blocks 1-2 m in diameter. During 25-26 October a dense white plume rose 500 m and drifted SW. The most active part of the lava flow advanced S down the Nima I drainage. Another part had advanced 3 km E and was active in the San José finca. Block avalanches were produced from the lava-flow fronts.
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.