INSIVUMEH reported in a special bulletin on 21 November that collapses of the fronts of lava flows on the NE, SE, S, and SW flanks of Santa María's Santiaguito lava-dome complex generated pyroclastic flows and ash plumes that rose 1 km. Ash plumes drifted 15 km S and SE, producing ashfall in Las Marías, Calaguache (9 km S), and Nuevo Palmar (12 km S). During 24-27 November incandescence was observed, lava flows were active on the SW and SE flanks, and ash plumes rose 500 m and drifted 15 km SW. On 27 November pyroclastic flows traveled short distances, and generated ash plumes that rose 500 m and drifted 10 km S and SE.

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)