INSIVUMEH reported that on 30 October heavy rainfall in the area triggered cold lahars which descended Santa María’s Cabello de Ángel (a tributary of Nima I) and San Isidro (tributary of El Tambor) drainages. The lahar in San Isidro carried blocks that were 1-2 m in dimeter. During 30-31 October explosions generated ash plumes that rose 800 m above the crater and drifted SW, causing ashfall in Monte Claro (S). Ash plumes from explosions rose as high as 1.1 km and drifted SE during 2-3 November; ash fell in finca El Faro (SW flank), La Florida (5 km S), San Marcos (10 km SW), and Palajunoj (18 km SSW).

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)