Strong eruption of Santa Maria produces moderate to strong ashfall, Guatemala

Strong eruption of Santa Maria produces moderate to strong ashfall, Guatemala

Santa Maria's Santiaguito lava-dome complex located in the western province of Quetzaltenango, Guatemala produced another strong eruption on April 19, 2016. The event was accompanied by moderate to strong ashfall affecting areas in the radius between 6 and 25 km (3.7 and 15.5 miles), including Loma Linda, San Marcos Palajunoj, and Retalhuleu. No significant damage was reported.

The eruption was caused by a partial collapse of the Caliente lava dome at 14:00 UTC (08:00 local time) and was likely followed by explosive activity, according to Volcano Discovery.

Pyroclastic flows have traveled for a couple of kilometers south and southeastward while an ash column was reported to rise to 4 500 m (14 764 feet) in altitude and drift 25 km (15.5 miles) southwestward.

The extent to which the ash plume was originating from the collapse or from the true explosive activity from accumulated, pressurized gasses is unknown. The increased effusion rate of viscous lava at the dome could be the main trigger, and collapsed avalanches could, in turn, have produced the co-ignimbrite ash plumes.

Pyroclastic flow from Santiaguito. Image credit: INSUVIMEH

An eruption of Santiaguito around 12:15 UTC on April 11, generated pyroclastic flows and ash plumes rising up to 6 km (20 000 feet) above the sea level. Volcanic ash at 4.2 km (14 000 feet) was 185 km (115 miles) west of summit while volcanic ash at 6 km (20 000 feet) was approximately 278 km (172 miles) southwest of the summit, Washington VAAC reported at 20:19 UTC. The Eruption was accompanied by loud rumbling.

The General Directorate of Civil Aviation was recommended to take precautions with air traffic in the area of fire and volcanoes, and take into account daily variations in the wind pattern. Tha National Park Pacaya was advised to maintain the ban on promotion to crater.

Geological summary

Symmetrical, forest-covered Santa María volcano is one of the most prominent of a chain of large stratovolcanoes that rises dramatically above the Pacific coastal plain of Guatemala. The 3772-m-high stratovolcano has a sharp-topped, conical profile that is cut on the SW flank by a large, 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 westward-younging vents, the most recent of which is Caliente. Dome growth has been accompanied by almost continuous minor explosions, with periodic lava extrusion, larger explosions, pyroclastic flows, and lahars. (GVP)

Featured image: Ash plume from Santiaguito, April 19, 2016. Image credit: CONRED

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