INSIVUMEH reported that on 26 and 29 June explosions from Santa María's Santiaguito lava dome complex produced ash plumes that rose to altitudes of 2.9-3.3 km (9,500-10,800 ft) a.s.l. and drifted W and SW. Fumarolic plumes rose 100-200 m above Caliente dome. On 26 June, the seismic network detected a lahar that traveled S down the Nima I river. Steam plumes and a sulfur odor rose from the deposits. The lahar was 15 m wide and 1 m thick at the toe, and carried blocks up to 1.5 m in diameter.

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)