INSIVUMEH reported that during 4-6 and 9-10 July an explosion from Santa María's Santiaguito lava-dome complex produced an ash plume that rose 300-800 m above Caliente dome and drifted SW. Ashfall was reported in La Florida (5 km S), Monte Claro (S), and Palajunoj (SW). Tephra avalanches from the lava dome traveled down the SE and SW flanks. During 7-8 July fumarolic plumes rose 200 m above the crater and drifted SW. One explosion generated an ash plume that rose 300 m and drifted SW. During 8-9 July gas plumes rose from the crater and avalanches descended the SE and SW flanks. Active lava flows were observed at night during 9-10 July; incandescent material traveled down the SE and SW flanks.

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)