Sangay volcano eruption in Ecuador produces large ash emission

eruption at sangay volcano - ash at 0630z april 21 2023

A notable eruptive pulse took place at Ecuador’s Sangay volcano on April 21, 2023, producing large volcanic ash emissions and ashfall west of the volcano.

Starting at 22:00 LT on April 20 (03:00 UTC on April 21), the RENSIG seismic stations detected emission tremors corresponding to an eruptive pulse from the Sangay volcano.1

This signal reached three peaks of activity — the first at 04:16 UTC, the second (stronger than the previous one) at 05:52 UTC, and the third (much weaker) at 07:50 UTC. The activity then gradually decreased until it disappeared around 09:00 UTC which indicates a total duration of the event of about 6 hours.

seismic signals sangay volcano eruption ecuador april 21 2023
Image credit: IG-EPN

Subsequently, at 16:50 UTC another pulse of activity was observed, but weaker than the previous ones.

The ash columns corresponding to this eruption reached heights of up to 9 km (29 500 feet) above the crater or about 14.3 km (46 900 feet) above sea level.

Slight to moderate ashfall was reported in the provinces of Chimborazo (Guamote and Pallatanga cantons), Bolívar (Chillanes canton), Los Ríos (Montalvo, Babahoyo, and Baba cantons), and Guayas (Salitre, Bucay, Juján, Simón Bolívar cantons).

sangay so2 and ash april 21 2023
ashfall from sangay volcano april 21 2023 igepn
Image credit: IG-EPN

This eruptive pulse is of lower intensity compared to the eruptive pulses of September 2020 and March 2021, IG-EPN said.

Based on the data compiled so far, it is estimated that its Volcanic Explosivity Index (VEI) was 2 on a scale that goes from 0 to 8 (Newhall and Self, 1982); which classifies it as a small eruption.

It is important to remember that these events are common in the Sangay volcano and that the main phenomena that can affect citizens are ashfall and secondary lahars in the event of heavy rains in the upper area of the volcano.

The nearby population was urged to take the appropriate measures to protect against ashfall and follow the information provided by official sources.

Sangay VA ADVISORY 20230421/1840Z

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.2

References:

1 Informe Volcánico Especial–Sangay N°2023-001 – Pulso eruptivo del volcán Sangayy caída de ceniza – IG-EPN – April 21, 2023

2 Sangay – Geological summary – GVP

Featured image credit: NOAA/GOES-East, RAMMB/CIRA, The Watchers. Acquired at 06:30 UTC on April 21, 2023

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