Explosive eruption at Sangay volcano, volcanic ash up to 11 km (36 000 feet) a.s.l., Ecuador


A strong explosive eruption took place at Sangay volcano, Ecuador at 23:15 UTC on July 9, 2021. Volcanic ash dispersed by 06:40 UTC on July 10.

According to the Washington VAAC, volcanic ash to 11 km (36 000 feet) above sea level was extending 45 km (28 miles) NE of the summit at 00:10 UTC on July 10. At the same time, volcanic ash to 7 km (20 000 feet) a.s.l. was extending 37 km (23 miles) WSW of the summit.

IGEPN reported their SAGA seismic station recorded a high-frequency signal possibly associated with lahars (mud and debris flow) on two occasions on July 9, and warned that continuous rainfall might trigger new flows.

This phenomenon has been recurrent in the current eruptive period since the rains in the volcano re-mobilize the accumulated material on the flanks, the institute said.

The proximity to rivers and their tributaries is not recommended.

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 (1 979 feet) 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: Sangay on June 10, 2021. Credit: Copernicus EU/Sentinel-2, Sentinel Playground, TW


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