Instituto Nacional de Sismología, Vulcanologia, Meteorologia e Hidrología (INSIVUMEH) reported that high-level eruptive activity continued at Santa Maria’s Santiaguito lava-dome complex during 13-20 August with lava extrusion, block collapses, and avalanches at the Caliente dome complex. The continuous effusion of blocky lava produced block avalanches on the dome’s flanks and occasional short-range pyroclastic flows that descended multiple flanks. Accumulated material formed a promontory upslope of the 2022 lava flows in the Zanjón Seco (SW) and San Isidro (W) drainages. During most nights and early mornings incandescence was visible around Caliente dome. Daily explosions generated gas-and-ash plumes that rose 700-900 m above the summit and drifted mainly NW, W, and SW. Ashfall was reported in areas downwind includinh Monte Claro (S) during 14-15 August and in San Marcos (8 km SW) and Loma Linda Palajunoj (7 km SW) during 18-19 August. On 18 August a lahar descended the Tambor river in the SSW sector of the volcano carrying sediment, tree trunks, branches, and volcanic blocks up to 1 m in diameter. The lahar was hot and had a sulfur odor.

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)