Tuesday 13 March 2018

Warning issued to shipping after increase in seismic activity beneath Kick 'em Jenny.

A warning has been issued to shipping after the University of the West Indies Seismic Research Centre in Trinidad detected an an increase in seismic activity beneath Kick 'em Jenny, a submarine volcano about 8 km to the north of Granada this week. Such tremors are often caused by the movement of hot water and volcanic gas beneath a volcano, which could indicate that the volcano is about to erupt. As a precaution a shipping exclusion zone surrounds the Kick 'em Jenny to a distance of 1.5 km; this zone has been increased to 5 km until further notice, due to the heightened risk to shipping during periods of activity.

The approximate location of Kick 'em Jenny. Google Maps.

 Kick 'em Jenny rises 1300 m above the surrounding seafloor, but remains 180 m below the surface. It was first discovered in July 1939, when an eruption broke the surface and threw material several hundred meters into the air, as well as generating a tsunami which was observed as far away as Barbados, though it was too small to cause any damage. However Kick 'em Jenny is labelled on many earlier maritime charts, indicating that people have been aware there was something here for several centuries, even if they did not know the nature of the feature.

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 Kick 'em Jenny 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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