INSIVUMEH reported that activity at Santa María’s Santiaguito lava-dome complex had increased on 29 January and remained elevated. Block-and-ash flows on 3 February descended the W and SW flanks and generated ash clouds that rose 600-800 m high and drifted W and NW. Ashfall was reported in San Martin Sacatepéquez (11 km NW), Llanos del Pinal (6 km NNE), Xecaracoj (7 km NNE), Loma Linda (6 km WSW), and El Palmar (12 km SSW), all in the department of Quetzaltenango. The report noted that during 30 January-3 February a total of 20 pyroclastic flows had traveled 1-3 km down the San Isidro drainage. Block-and-ash flows descended the W, SW, and NE flanks during 3-4 February. A lahar descended the San Isidro River, a SSW-flank tributary of the Tambor River, on 8 February.

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.

Sources: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH), Coordinadora Nacional para la Reducción de Desastres (CONRED)