Report on Santa Maria (Guatemala) — 21 August-27 August 2013
Smithsonian / US Geological Survey Weekly Volcanic Activity Report, 21 August-27 August 2013
Managing Editor: Sally Kuhn Sennert
Please cite this report as:
Global Volcanism Program, 2013. Report on Santa Maria (Guatemala). In: Sennert, S K (ed.), Weekly Volcanic Activity Report, 21 August-27 August 2013. 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 constant lava extrusion from Santa María's Santiaguito lava-dome complex on 22 August. At 1745 a series of collapses of the SE crater rim generated pyroclastic flows that reached the S and SE base of the complex. Bombs were ejected 500 m SW and ash plumes rose 4 km. A weak explosion on 23 August generated a white plume that rose 600 m. Ashfall was reported in the Palajunoj region (S).
At 0815 on 24 August a partial collapse of the SE crater rim of Caliente cone was accompanied by an explosion heard 20 km away and a shock wave. The explosion also rattled homes within 10 km. The collapse was followed by pyroclastic flows, avalanches, and more explosions. At 2210 another similar collapse occurred, producing a blast heard 15 km away and pyroclastic flows that descended the SE flank. Houses within 10 km again vibrated. Ash plumes rose as high as 4 km and drifted W and SW. On 25 August explosions continued and block avalanches descended the E flank of Caliente cone. At 0324 on 27 August a moderate explosion produced a mushroom-shaped ash plume that rose 1.3 km, and drifted SW, causing ashfall in Palajunoj. A pyroclastic flow traveled SW, and avalanches traveled S and E. White gas plumes rose 1.2 km.
Geologic Background. Symmetrical, forest-covered Santa María volcano is one of the most prominent of a chain of large stratovolcanoes that rises dramatically above the Pacific coastal plain of Guatemala. The stratovolcano has a sharp-topped, conical profile that 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 westward-younging vents, the most recent of which is Caliente. Dome growth has been accompanied by almost continuous minor explosions, with periodic lava extrusion, larger explosions, pyroclastic flows, and lahars.