During 10-16 September INSIVUMEH reported white fumarolic plumes rising 150-500 m above Santa Maria’s active cone, Santiaguito. The active lava flow on the E flank continued to generate ash plumes and incandescence. On 14 September INSIVUMEH observed that the lava flow advancing within the Nimá 1 drainage had reached a total of 3,500 m from the summit.

INSIVUMEH reported hot lahars in the drainages of Cabello de Ángel and Río Nimá 1 on 11 September. Tree trunks and branches were entrained and the flow was 20 m wide and 2 m deep. Moderate vibrations could be felt from the ground as it passed the observatory; sulfur odors were also noticed.

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)