INSIVUMEH reported that during 6-11 March explosions from Santa María's Santiaguito lava-dome complex produced ash plumes that rose 700-900 m and drifted S, SE, and E. Ashfall was reported in Calahuaché, El Faro (SW flank), and San José Patzulin (SW flank). Avalanches from lava-flow fronts traveled down the flanks. On 8 March avalanches from the NE part of the lava dome generated ashfall on the volcano. During 11-12 March four lava flows were active, on the SW, S, SE, and E flanks, which sometimes produced avalanches that generated pyroclastic flows. The number of explosions ranged from 40 to 60 per day, often producing ash plumes that rose 0.5-1 km above the complex.

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)