On 13-19 August INSIVUMEH reported that fumarolic columns rose to 2.7-2.8 km (8,800-9,200 ft) a.s.l. above Santiaguito, drifting to the S and SW. On most days the lava flow (2.5 km in length) moved towards and into Nima Canyon I. Collapse avalanches from the lava flow front generated columns of fine ash that rose 1.2-2 km (3,900-6,600 ft) a.s.l. , drifting over the Palajunoj area on 15 August. On 13-16 and 19 August INSIVUMEH reported white degassing plumes rising 200-400 above the crater and drifting SW, and noted decreased incandescence at the crater.

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 E 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)