INSIVUMEH reported that during 8-9 March a pyroclastic flow from Santa María's Santiaguito lava dome complex traveled down the E flank, depositing material in Rio Nima I. An ash plume rose 1 km and drifted E. Ashfall was reported in Quetzaltenango (10 km NNE) and Retalhuleu (27 km SW) from plumes produced during the previous few days. Based on analyses of satellite imagery, the Washington VAAC reported that ash-and-gas plumes drifted 22 km SW and 19 km W on 10 March.

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.

Sources: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH), Washington Volcanic Ash Advisory Center (VAAC)