INSIVUMEH reported that the eruption at Santa Maria’s Santiaguito lava dome complex continued during 20-27 June, with effusion of lava flows, explosions, and avalanches. Dome growth sometimes produced avalanches and short pyroclastic flows that traveled down the S, SW, and W flanks. Weak and moderate explosions were recorded daily. Explosions also triggered dome collapses, resulting in weak and moderate debris avalanches that descended the flanks in many directions. Incandescence at the crater and along lava flow margins was visible during most nights and early mornings. During 20-21 June ash-and-gas plumes rose 800 m and drifted W and SW. On 23 June a lahar descended the Río Cabello de Ángel, a tributary of the Nimá I and Samalá rivers on the E flank. The lahar consisted of a mixture of fine volcanic material, water, volcanic blocks up to 1 m in diameter, and tree trunks and branches.

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)