During 26 June-2 July, INSIVUMEH reported that ash plumes frequently rose from Santa María's Santiaguito lava-dome complex. Explosions during 26-28 June generated ash plumes that rose at most 900 m and drifted SW; ashfall was reported in Monte Claro (S) and Finca La Florida (5 km S) during 27-28 June. Avalanches originated from the lava flow on the S flank and from the SW lava dome, and produced pyroclastic flows on 27 June. An explosion at dawn on 28 June produced rumbling and degassing noises. Four moderate explosions during the morning of 30 June generated ash plumes that rose as high as 1 km and drifted S and SE. Rockfalls occurred on the flanks, and ash fell in San José, La Quina, and the region of Calahuaché. Explosions during 1-2 July generated incandescent avalanches from the S dome; a white plume rose 300 m above the crater. Gray plumes rose 400 m and drifted N.

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)