INSIVUMEH reported that on 11 October a moderate lahar descended the Cabello de Ángel and the Nimá I drainages, both tributaries of the Salama river. During 12-13 October ash plumes generated by explosions rose 500 m above the crater rim and drifted SE, causing ashfall in Finca San José. Avalanches of material descended the SE part of the lava dome. On 13 October the seismic network detected moderate-to-strong lahars in the Cabello de Ángel and the Nimá I drainages triggered by heavy rain. Explosions during 13-14 October produced ash plumes that drifted SW, causing ashfall in La Florida (5 km S) ranch. Ash plumes from explosions detected during 15-16 October rose 600 m and drifted S. Ash fell locally around the volcano. Avalanches of material descended the NE and SE parts of the lava dome.

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)