INSIVUMEH reported that on 13 June lahars descended Nimá I drainage on the S flank of Santa María's Santiaguito lava-dome complex. The lahars were 15-18 m wide and 1-2 m deep, and carried blocks 1.5 m in diameter and tree branches. CONRED noted that a Yellow Alert Level was declared for Quetzaltenango (18 km WNW) on 16 June due to continuing rains and an increased threat of lahars. Weak explosions during 16-18 June generated diffuse ash plumes that rose 700 m above the complex and drifted SW and W.

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)