INSIVUMEH reported that the eruption at Santa María’s Santiaguito lava-dome complex continued during 22-28 February. Effusion from Caliente dome fed lava flows that slowly descended the San Isidro and Zanjón Seco drainages on the W and SW flanks. Incandescence from the dome and the lava flows was visible nightly. Block-and-ash flows from the dome, and from both the ends and sides of the flows, descended the S, SW, and W flanks almost daily. Ash plumes from the avalanches and from occasional explosions at the summit rose a few hundred meters high; during 22-23 February ash plumes rose 700 m above the summit and drifted WNW.

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)