INSIVUMEH reported that on 19 June an explosion from Santa María's Santiaguito lava-dome complex generated a white plume that rose 700 m and drifted SW. On 20 June lahars that descended the Nimá I and Tambor river drainages on the S flank were 30 m wide and 3 m thick. The lahar in Nimá I carried blocks up to 3 m wide as well as branches and tree trunks. The lava dome continued to grow on 22 June and fed a lava flow that traveled S, which produced avalanches from the flow front. An explosion on 23 June generated a gray plume that rose 500 m and drifted SW, causing ashfall in Monte Claro (S). On 23 and 25 incandescent avalanches descended the S flank. Explosions on 25 June produced ash plumes that rose 700-1,000 m and drifted 10 km S and SW.

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)