INSIVUMEH and CONRED reported that on 12 June lahars 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 was 15-17 m wide and 1.5 m deep, and carried shrubs, tree trunks, and blocks up to 2 m in diameter. On 16 June lahars again descended the San Isidro drainage.

During 15-18 June explosions at Caliente cone generated ash plumes that rose 400-800 m and drifted SW and E. Avalanches of material descended the E and SE flanks of the cone, and during 17-18 June reached the base of the cone. Minor ashfall was reported in San Marcos (10 km SW), Loma Linda (6 km WSW), and Palajunoj (18 km SSW) during 17-18 June.

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