INSIVUMEH reported that during 1-2 November explosions from Santa María's Santiaguito lava-dome complex generated ash plumes that rose 600-1,000 m above the complex and drifted S and SW, causing ashfall in villages downwind. The explosions were heard in areas 12 km to the S and SW. Lava flows on the SE and S flanks generated block avalanches. During 3-4 and 7-8 November explosions produced ash plumes that rose 500-800 m above the complex and drifted SW and W. Explosions and rumbling were heard in areas to the S and SW. Lava flows on the SE flank continued to generate block avalanches. .

Based on analyses of satellite imagery, the Washington VAAC reported that during 5-6 November possible ash plumes drifted 18-28 km SE and a thermal anomaly over the volcano was detected. On 8 November a possible ash plume drifted 45 km SW, coincident with an enhanced thermal anomaly.

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)