INSIVUMEH reported that eruptive activity continued at Santa Maria’s Santiaguito lava dome complex during 23-31 January with a lava extrusion at the Caliente dome. Daily reports were not available on 29 and 30 January. Incandescence from the dome was visible during most nights and early mornings. Explosions occurring at a rate of 1-6 per hour on most days generated gas-and-ash plumes that rose 600-900 m above the dome and drifted mainly NW, W, and SW. The explosions produced block avalanches on the dome’s W, SW, S, and E flanks and generated occasional, short-range pyroclastic flows that predominantly descended the W, SW, and S flanks. Block avalanches were visible from the margins of the upper part of the lava flow on the SW flank. Ashfall occurred in Loma Linda (7 km W) and San Marcos Palajunoj (8 km SW) during 25-26 January.

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)