Explosive activity at Sangay volcano, ash plume to 7 000 m (23 000 feet) a.s.l., Ecuador


Explosive activity continues at Sangay volcano in Ecuador. On Tuesday, January 21, 2020, the Washington VAAC warned about a volcanic ash plume that rose up to approximately 7 000 m (23 000 feet) above sea level.

On January 20, the center issued a report saying they received information suggesting a possible emission. As the eruptive activity went on, the center warned about a volcanic ash plume that rose up to around 6 100 m (20 000 feet) a.s.l. In addition, the plume reportedly looks to be a mixture of ash and gases.

On January 21, the plume rose up to 7 000 m (23 000 feet) a.s.l. 

The Ecuadorian Geophysical Institute of the National Polytechnic School (IG EPN) reported the emission of gas and ash content, using images provided by the ECU 911 that also showed the incandescent blocks on the southeastern flank of the volcano on Monday, January 20.

The institute said similar activity has been going on over the past few weeks, but good weather conditions on Monday enabled them to observe the volcano. 

Based on information from the Guayaquil MWO, satellite and webcam images, and wind model data, the Washington VAAC reported that from January 1 to 11, 2020, ash plumes from rose to 5.2 – 6.7 km (17 000 – 22 000 feet) a.s.l. and drifted in multiple directions. Crater incandescence was identified in satellite images on January 9 and 10.

At the beginning of December 2019, IG reported that the eruption at Sangay that began on May 7 was continuing as of December 4 without a notable increase or decrease in activity levels.

The activity was concentrated at two eruptive centers: the Central Crater and the Ñuñurcu dome (located 190 m / 623 feet SSE of Central Crater). Sporadic explosions at Central Crater produced ash plumes that rose as high as 2 km (6 500 feet) above the crater rim and drifted mainly NE during the previous month.

Minor ashfall was recorded in the towns of Alao (20 km / 12.4 miles NW), Cebadas (35 km / 21.7 WNW), and Guaguallá (Chimborazo province), in Macas (42 km / 26 miles SSE, Morona-Santiago province), and in the Azuay province.

Almost continuous lava effusion from the Ñuñurcu dome fed lava flows that traveled down the SE flank.

The first known eruption of this volcano started in October 1628 (VEI 3). Another VEI 3 eruptive period started in 1728 and ended around 1916. Another VEI 3 period started in 1934 and ended in 2011. With brief quiet periods, VEI 1 to 2 activity continues to date.

Geological summary

The isolated Sangay volcano, located east of the Andean crest, is the southernmost of Ecuador's volcanoes and its most active. The steep-sided, glacier-covered, dominantly andesitic volcano grew within horseshoe-shaped calderas of two previous edifices, which were destroyed by collapse to the east, producing large debris avalanches that reached the Amazonian lowlands.

The modern edifice dates back to at least 14,000 years ago. It towers above the tropical jungle on the east side; on the other sides flat plains of ash have been sculpted by heavy rains into steep-walled canyons up to 600 m deep. The earliest report of a historical eruption was in 1628. More or less continuous eruptions were reported from 1728 until 1916, and again from 1934 to the present. The almost constant activity has caused frequent changes to the morphology of the summit crater complex. This volcano is located within the Sangay National Park, a UNESCO World Heritage property.

Featured image credit: IG EPN 

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