INSIVUMEH reported that active lava flows on the S and SE flanks of Santa María's Santiaguito lava-dome complex generated block avalanches during 1-3 February. Explosions sent ash plumes 500-600 m above the complex that drifted S, SW, and WSW. Ashfall was reported in Monte Claro (S) and Palajunoj (SW) on 1 February, and in La Florida (5 km S), San Marcos (46 km NW), and Palajunoj during 2-3 February. Strong winds caused re-suspended ash to rise 1 km high and drift several kilometers W and S. Rumbling noises were heard 15 km away on the S and W flanks during 1-3 February. Gas plumes rose 500 m above the Caliente Cone and drifted S and SW during 2-3 February.

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)