INSIVUMEH reported that during 16-17 February explosions from Santa María's Santiaguito lava dome complex produced ash plumes that rose 800 m above Caliente dome and drifted S and SW. Avalanches traveled S, and ashfall was reported in Palajunoj, on the SW flank. According to the Washington VAAC, ash plumes were observed in satellite imagery drifting more than 10 km SSW. During 18-19 February, thermal anomalies were detected in satellite imagery. An ash plume drifted 25 km W on 18 February and again W at an altitude of 3.4 km (11,000 ft) a.s.l. on 19 February.

INSIVUMEH reported that during 20-21 February activity was low. Explosions produced ash plumes that rose up to 500-900 m above Caliente dome. On 21 February a few avalanches and pyroclastic flows accompanied the explosions. Incandescent avalanches originated from the top of Caliente dome on 22 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.

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