Friday 9 April 2021

Eruption on La Soufrière volcano, St Vincent Island.

La Soufrière volcano on the island of St Vincent in St Vincent and the Grenadines, part of the Windward Islands group in the Lesser Antilles Islands of the Caribbean, erupted on Friday 9 April 2021, according to the National Emergency Management Organisation. The volcano erupted slightly after 8.40 am local time, producing an ash column that rose about 6000 m above the island. There have been no reports of any casualties associated with this event, but many communities have reported ash-falls, and much of the north of the island has been evacuated as a precautionary measure. 

An ash column above the island of St Vincent on 9 April 2021. University of the West Indies Seismic Research Centre.

La Soufrière is a 1220 m stratovolcano (cone shaped volcano made up of layers of ash and lava) situated at the northern end of the island of St Vincent. It is the youngest, and northernmost, of a chain of volcanoes that make up the island, and is thought to have first erupted around 2380 BC.

The Lesser Antilles are located at the eastern fringe of the Caribbean Tectonic Plate. The Atlantic Plate (strictly speaking, an extension of the South American Plate which runs to the northeast of the Caribbean) is being subducted beneath this, and as it sinks into the Earth, is melted by the heat of the planets interior. Some of the melted material then rises up through the overlying Caribbean Plate as magma, fuelling La Soufrière and the other volcanoes of the Lesser Antilles Volcanic Arc. The subduction of the Atlantic Plate beneath the Caribbean Plate is not a smooth process, with the two plates constantly sticking together then breaking apart as the tectonic pressure builds up, causing Earthquakes in the process, though since the boundary between the two plates is some way to the east of the islands, Earthquakes in the Lesser Antilles tend to be both deep and offshore, which lessens their destructive potential.

The subduction of the Atlantic Plate beneath the Caribbean Plate fuels the volcanoes of the Lesser Antilles Volcanic Arc. George Pararas-Carayannis.

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