Thursday 22 April 2021

Magnitude 5.5 Earthquake off the coast of Valparaiso, Chile.

The United States Geological Survey recorded a Magnitude 5.5 Earthquake at a depth of 7.5 km, off the coast of the city of Valparaiso in Chile, slightly after 8.15 pm local time on Wednesday 21 April 2021 local time (slightly after 0.15 am on Thursday 22 April GMT). There are no reports of any injuries associated with this event, but people have reported feeling it around Valparaiso.

The location of the 21 April 2021 Valparaiso Earthquake. USGS.

Chile is located on the west coast of South America, which is also the convergent margin between the Nazca and South American Plates. The Nazca Plate is being subducted beneath the South American Plate and is sinking beneath the South American Plate. This is not a smooth process, the rocks of the two plates continuously stick together then, as the pressure builds up, break apart again, causing Earthquakes. As the Nazca Plate sinks deeper it is partially melted by the heat of the Earth's interior. Some of the melted material then rises up through the overlying South American Plate as magma, fuelling the volcanoes of the Chilean Andes.

The subduction of the Nazca Plate beneath the South American Plate, and how it causes Earthquakes and volcanoes. Pacific Earthquake Engineering Research Center.

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