The United States Geological Survey recorded a Magnitude 4.7 Earthquake at a depth of 22.2 km roughly beneath western Antigua in the Lesser Antilles, slightly before 4.30 pm local time (slightly before 8.30 pm GMT) on Tuesday 17 April 2018. This was a moderate quake, and at some depth as well as some way offshore, and there are no reports of any casualties or serious damage, though the quake was felt on the islands of Antigua, Nevis, Saint Kitts, Montserat, and Guadeloupe.
The approximate location of the 9 February 2018 Lesser Antilles Earthquake. USGS.
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 the 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.
Witness accounts of Earthquakes can help geologists to understand these events, and the structures that cause them. The international non-profit organisation Earthquake Report is interested in hearing from people who may have felt this event; if you felt this quake then you can report it to Earthquake Report here.
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